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

This reverts commit 4d3b2bd9 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.  It's not a "real" break, and
we can work around it, but this really does not affect Android systems,
so it's safe to drop for now.

Bug: 161946584
Change-Id: Id2666dca715b44594f71e291a4c01e5b5a0e88d9
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>