libfc: Update rport reference counting

libfc: Update rport reference counting

Originally libfc would just be initializing the refcount to '1', and
using the disc_mutex to synchronize if and when the final put should be
happening.  This has a race condition as the mutex might be delayed,
causing other threads to access an invalid structure.  This patch
updates the rport reference counting to increase the reference every
time 'rport_lookup' is called, and decreases the reference
correspondingly.  This removes the need to hold 'disc_mutex' when
removing the structure, and avoids the above race condition.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Vasu Dev <vasu.dev@intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
OraBug: 27363267
(cherry picked from commit baa6719f902af9c03e528b08dfb847de295b5137)
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Fred Herard <fred.herard@oracle.com>
Signed-off-by: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>