BUG:New epoch in matplotlib 3.3 causes plotting issues
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [x] (optional) I have confirmed this bug exists on the master branch of pandas.

---

**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

```python
import pandas as pd
import matplotlib.pyplot as plt

ndx = pd.to_datetime(['2020-07-1 04:01:34', '2020-07-2 04:03:33', '2020-07-3 04:05:33',
                      '2020-07-4 04:07:35', '2020-07-5 04:09:35']) 
df = pd.DataFrame(index=ndx, data={'Vsw': [389.4, 388.5, 384.5, 384.7, 386.6]})
print(df.info())
ax1 = df['Vsw'].plot(xlim=['2020-7-1', '2020-7-6'])
print(ax1.get_xlim(), '\n\n\n')
plt.show()

# plot without specifying x limits
ax2 = df['Vsw'].plot()
print(ax2.get_xlim(), '\n\n\n')
plt.show()

# plot from a DataFrame with a pd.date_range index
df = pd.DataFrame(index=pd.date_range('2020-7-1', '2020-7-5', freq='D'),
                  data={'Vsw': [389.4, 388.5, 384.5, 384.7, 386.6]})
print(df.info())
ax3 = df['Vsw'].plot(xlim=['2020-7-1', '2020-7-6'])
print(ax3.get_xlim())
plt.show()

```

#### Problem description

See https://matplotlib.org/3.3.0/users/whats_new.html#dates-use-a-modern-epoch

The first plot is blank. get_xlim returns (18444.0, 18449.0)  The second plot contains the values being plotted and get_xlim returns (737606.9674762732, 737611.3736001157).  The third plot shows the plotted values and get_xlim returns (18444.0, 18449.0).

If the epoch is set to the old epoch value with 
import matplotlib.dates as mpld
mpld.set_epoch('0000-12-31T00:00:00')
all three plots show the plotted values.  get_xlim returns (737607.0, 737612.0) for the first plot, (737606.9674762732, 737611.3736001157) for the second and (18444.0, 18449.0) for the third.

#### Expected Output

The three plots should show the values being plotted whether or not xlim is specified in the plot() command or the DatetimeIndex has a Freq value

#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit           : 65090286608602ba6d67ca4a29cf0535156cd509
python           : 3.8.4.final.0
python-bits      : 64
OS               : Darwin
OS-release       : 19.6.0
Version          : Darwin Kernel Version 19.6.0: Sun Jul  5 00:43:10 PDT 2020; root:xnu-6153.141.1~9/RELEASE_X86_64
machine          : x86_64
processor        : i386
byteorder        : little
LC_ALL           : None
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.1.0.dev0+2131.g650902866
numpy            : 1.19.0
pytz             : 2020.1
dateutil         : 2.8.1
pip              : 20.1.1
setuptools       : 47.3.1
Cython           : 0.29.20
pytest           : None
hypothesis       : None
sphinx           : 3.1.1
blosc            : None
feather          : None
xlsxwriter       : 1.2.9
lxml.etree       : 4.5.1
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.16.1
pandas_datareader: None
bs4              : 4.9.1
bottleneck       : 1.3.2
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : 3.3.0
numexpr          : 2.7.1
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
pyxlsb           : None
s3fs             : None
scipy            : 1.5.0
sqlalchemy       : 1.3.18
tables           : None
tabulate         : None
xarray           : None
xlrd             : 1.2.0
xlwt             : None
numba            : 0.50.1

</details>
