BACKPORT: xfrm: Allow Output Mark to be Updated Using UPDSA

Allow UPDSA to change "output mark" to permit
policy separation of packet routing decisions from
SA keying in systems that use mark-based routing.

The set mark, used as a routing and firewall mark
for outbound packets, is made update-able which
allows routing decisions to be handled independently
of keying/SA creation. To maintain consistency with
other optional attributes, the output mark is only
updated if sent with a non-zero value.

The per-SA lock and the xfrm_state_lock are taken in
that order to avoid a deadlock with
xfrm_timer_handler(), which also takes the locks in
that order.

Signed-off-by: Nathan Harold <nharold@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

(cherry picked from commit 6d8e85ffe17895d7bc632dfbaa9e2e33b22fe873)
Backport resolution required using props.output_mark instead of
props.smark

Change-Id: I08c7bfc114ac9826a8a18f5ac1c3ff17a4e0940b
Signed-off-by: Benedict Wong <benedictwong@google.com>
Bug: 114060045