scsi: megaraid_sas: Do not fire DCMDs during PCI shutdown/detach

This patch addresses the issue of driver firing DCMDs in PCI
shutdown/detach path irrespective of firmware state.  Driver will now
check whether firmware is in operational state or not before firing
DCMDs. If firmware is in unrecoverable state or does not become
operational within specfied time, driver will skip firing DCMDs.

[mkp: fixed typos]

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan Srikanteshwara <shivasharan.srikanteshwara@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>