scsi: mpt3sas: Pre-allocate RDPQ Array at driver boot time.

Instead of allocating RDPQ array (This stores the address's of each RDPQ
pools) at run time, now it will be allocated once during driver load
time and same will be reused during host reset operation also (instead
of allocating & freeing this buffer on the fly during every host reset
operation) and then freed during driver unload.

Signed-off-by: Chaitra P B <chaitra.basappa@broadcom.com>
Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>