BUG: Incorrect TypeError for CategoricalIndex.view('i8')
xref https://github.com/pandas-dev/pandas/pull/25447#discussion_r260730337

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

```python
import pandas.util.testing as tm
ind = tm.makeCategoricalIndex(100)
ind.view('i8')
```
#### Problem description

```python-traceback
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-11-5cb1f6f042dd> in <module>()
      1 import pandas.util.testing as tm
      2 ind = tm.makeCategoricalIndex(100)
----> 3 ind.view('i8')

~\Anaconda3\lib\site-packages\pandas\core\indexes\base.py in view(self, cls)
    913         # index type here
    914         if cls is not None and not hasattr(cls, '_typ'):
--> 915             result = self._data.view(cls)
    916         else:
    917             result = self._shallow_copy()

TypeError: view() takes 1 positional argument but 2 were given
```

#### Expected Output

```python-traceback
TypeError: Cannot change data-type for object array
```

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

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.5.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 69 Stepping 1, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.23.0
pytest: 3.5.1
pip: 10.0.1
setuptools: 39.1.0
Cython: 0.28.2
numpy: 1.14.3
scipy: 1.1.0
pyarrow: None
xarray: None
IPython: 6.4.0
sphinx: 1.7.4
patsy: 0.5.0
dateutil: 2.7.3
pytz: 2018.4
blosc: None
bottleneck: 1.2.1
tables: 3.4.3
numexpr: 2.6.5
feather: None
matplotlib: 2.2.2
openpyxl: 2.5.3
xlrd: 1.1.0
xlwt: 1.3.0
xlsxwriter: 1.0.4
lxml: 4.2.1
bs4: 4.6.0
html5lib: 1.0.1
sqlalchemy: 1.2.7
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
</details>
