This patch adds general RSCN support:

 - The ability to transmit an RSCN to the port on the other end of
   the link (regular port if pt2pt, or fabric controller if fabric).
 - And general recognition of an RSCN ELS when an ELS is received.
Signed-off-by: NDick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: NJames Smart <jsmart2021@gmail.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NArun Easi <aeasi@marvell.com>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>