BUG: pd.crosstab fails when passed multiple columns, margins True and normalize True
- [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.

---

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

```python
import pandas as pd

df = pd.DataFrame({"A": ["foo", "foo", "foo", "foo", "foo",
          "bar", "bar", "bar", "bar"],
                    "B": ["one", "one", "one", "two", "two",
                          "one", "one", "two", "two"],
                    "C": ["small", "large", "large", "small",
                          "small", "large", "small", "small",
                          "large"],
                    "D": [1, 2, 2, 3, 3, 4, 5, 6, 7],
                    "E": [2, 4, 5, 5, 6, 6, 8, 9, 9]})

pd.crosstab(index=df.C,
            columns=[df.A,df.B],  
            margins=True,
            margins_name='Sub-Total',
            normalize='all')

# returns ValueError: Sub-Total not in pivoted DataFrame
```

#### Problem description

#27663 found that `pd.crosstab` failed when `margins` and `normalize` were true.  This continues to be the case when more than one column is passed. 

This is not the case when a single column and multiple rows is passed.


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


INSTALLED VERSIONS
------------------
commit           : None
python           : 3.7.7.final.0
python-bits      : 64
OS               : Windows
OS-release       : 10
machine          : AMD64
processor        : Intel64 Family 6 Model 142 Stepping 9, GenuineIntel
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : None.None

pandas           : 1.0.3
numpy            : 1.18.1
pytz             : 2020.1
dateutil         : 2.8.1
pip              : 20.0.2
setuptools       : 47.1.1.post20200604
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : 3.1.1
blosc            : None
feather          : None
xlsxwriter       : 1.2.9
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : 2.8.4 (dt dec pq3 ext lo64)
jinja2           : 2.11.2
IPython          : 7.13.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fastparquet      : None
gcsfs            : None
lxml.etree       : None
matplotlib       : 3.1.3
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
pytest           : None
pyxlsb           : None
s3fs             : None
scipy            : 1.4.1
sqlalchemy       : 1.3.17
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
xlsxwriter       : 1.2.9
numba            : None

<details>

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