scsi: megaraid_sas: Replace sdev_busy with local counter

scsi: megaraid_sas: Replace sdev_busy with local counter

Use local tracking of per-sdev outstanding command since sdev_busy in SCSI
mid layer is improved for performance reason using sbitmap (earlier it was
atomic variable).

Link: https://lore.kernel.org/r/20210122023317.687987-11-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>