Revert "crypto: ahash - Set default reqsize from ahash_alg"

This reverts commit 3a0c8429 which is
commit 9e01aaa1 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I29c21260e15c6e3982fe7eccd38330f470fa0167
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>