The docs job has recently begun failing with:
autodoc: failed to import module 'connector' from module
'os_brick.initiator'; the following exception was raised: No module
named 'cryptography'
We're not directly importing cryptography in os-brick, so address this
by adding 'cryptography' to the autodoc_mock_imports list.
Change-Id: I5128d717f7a31fb9042f690ed7c17a3191f1a99e
c187a33b7b