scsi: smartpqi: enhance BMIC cache flush

scsi: smartpqi: enhance BMIC cache flush

 - distinguish between shutdown and non-shutdown.

Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Signed-off-by: Kevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from commit 58322fe0069a2ae2a19cf29023cc0b82c7245762)

Orabug: 26943380

Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>