Update email address for stable patch submission

The stable@kernel.org email address has been replaced with the
stable@vger.kernel.org mailing list.  Change the stable kernel rules to
reference the new list instead of the semi-defunct email alias.

CC: <stable@kernel.org>
CC: <stable@vger.kernel.org>
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>