scsi: megaraid_sas: Add support for FW snap dump

Latest firmware adds a mechanism to save firmware logs just before
controller reset on pre-allocated internal controller DRAM. This feature is
called snapdump which will help debugging firmware issues.  This feature
requires extra time and firmware reports these values through new driver
interface. Before initiating an OCR, driver needs to inform FW to save a
snapdump and then wait for a specified time for the snapdump to complete.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>