Revert "net: dev: Convert sa_data to flexible array in struct sockaddr"

This reverts commit fd84a5fa which is
commit b5f0de6d 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: Iecd4acaa6f3d416b1fe7b928d3b4f069bf61861e
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>