Revert "Fix race for duplicate reqsk on identical SYN"

This reverts commit 527bec1f which is
commit ff46e3b4 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: I9633c90950b3cbd29055583a40e07ee9bb39b2f9
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>