scsi: efct: Decrease area under spinlock

Under the session level spinlock node->active_ios_lock in
efct_scsi_io_alloc() we are taking another spinlock for the port.  This
leads to contention between sessions and even between I/Os in the same
session.

Reduce the locked region to active_ios list for which active_ios_lock is
intended. Spinlock CPU usage decreases from 18% down to 13%. IOPS are
increased from 220 kIOPS to 264 kIOPS for one LUN.

Link: https://lore.kernel.org/r/20210914105539.6942-4-d.bogdanov@yadro.com


Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Ram Vegesna <ram.vegesna@broadcom.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>