selinux: fix broken peer recv check

Fix a broken networking check. Return an error if peer recv fails.  If
secmark is active and the packet recv succeeds the peer recv error is
ignored.

Signed-off-by: Chad Hanson <chanson@trustedcs.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>