Fix changes introduced to volatility3.framework.constants in PRs #838

[gcmoreira]

Trying to use the changes in #1247 I found that the following works

>>> from volatility3.framework.constants.architectures import LINUX_ARCHS
>>> LINUX_ARCHS
['Intel32', 'Intel64']

However, the following fails:

>>> from volatility3.framework.constants import architectures
>>> architectures.LINUX_ARCHS
Traceback (most recent call last):
  File "<string>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'LINUX_ARCHS'

Debugging why the import doesn't fail but instead gets a None, which is really weird, I found this happens because the changes introduced to support deprecated constants in PRs #838 in this line.

Completely removing the __getattr__() function works as expected.

>>> from volatility3.framework.constants import architectures
>>> architectures.LINUX_ARCHS
['Intel32', 'Intel64']

The changes in this PR keep the __getattr__() function while still allowing the use of sub-modules of volatility3.framework.constants.

>>> from volatility3.framework.constants import architectures
>>> architectures.LINUX_ARCHS
['Intel32', 'Intel64']

[ikelos]

Looks good, sorry for the mistake first time around.... 5:)