scsi: smartpqi: update kexec and power down support

Add PQI reset to driver shutdown callback to work around controller bug.

During an 1.) OS shutdown or 2.) kexec outside of a kdump, the Linux
kernel will clear BME on our controller.

If BME is cleared during a controller/host PCIe transfer, the controller
will lock up.

So we perform a PQI reset in the driver's shutdown callback function to
eliminate the possibility of a controller/host PCIe transfer being
active when the kernel clears BME immediately after calling the driver's
shutdown callback.

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>