scsi: aacraid: Allow reset_host sysfs var to recover Panicked Fw

It is possible to restart the controller via the use of the reset_host
sysfs variable. This does work for controllers that can no longer respond,
since driver will attempt to send down a shutdown in this path.

Check if the controller is able to receive commands before sending down
a shutdown

Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>