scsi: smartpqi: Fix PCI control linkdown system hang

scsi: smartpqi: Fix PCI control linkdown system hang

Fail all outstanding requests after a PCI linkdown.

Block access to device SCSI attributes during the following conditions:

  "Cable pull" is called PQI_CTRL_SURPRISE_REMOVAL.

  "PCIe Link Down" is called PQI_CTRL_GRACEFUL_REMOVAL.

Block access to device SCSI attributes during and in rare instances when
the controller goes offline.

Either outstanding requests or the access of SCSI attributes post linkdown
can lead to a hang.

Post linkdown, driver does not fail the outstanding requests leading to
long wait time before all the IOs eventually fail.

Also access of the SCSI attributes by host applications can lead to a
system hang.

Link: https://lore.kernel.org/r/165730603578.177165.4699352086827187263.stgit@brunhilda
Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Sagar Biradar <sagar.biradar@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>