Revert "tcp: Fix data-races around sysctl_tcp_syn(ack)?_retries."

This reverts commit 7b008491 which is
commit 20a3b1c0 upstream.

It breaks the Android abi.  If it is required in the future, it can come
back in an abi-safe way.

Bug: 161946584
Change-Id: Id6fdb41a7797ed851cc37b4fe141fc69a069b640
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>