Revert "net: Fix TOCTOU issue in sk_is_readable()"

This reverts commit c2b26638 which is
commit 2660a544 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: Ib2d18080c1dc4b9b44ae64d406f8b9b38a845ac7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>