scsi: mpt3sas: Do not mark fw_event workqueue as WQ_MEM_RECLAIM

The firmware event workqueue should not be marked as WQ_MEM_RECLAIM
as it's doesn't need to make forward progress under memory pressure.
In the current state it will result in a deadlock if the device had been
forcefully removed.

Cc: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Cc: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Acked-by: Sreekanth Reddy <Sreekanth.Reddy@broadcom.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>