scsi: megaraid_sas: Error handling for invalid ldcount provided by firmware in RAID map

Currently driver does not validate ldcount provided by firmware.  If the
value is invalid, fail RAID map validation accordingly.  This issue is
rare to hit in field and is fixed as part of code review.

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>