Correct driver's ISR accessing a data structure member that has not been
fully initialized during driver initialization.

The pqi queue groups can have uninitialized members when an interrupt
fires. This has not resulted in any driver crashes. This was found during
our own internal testing. No bugs were ever filed.

Link: https://lore.kernel.org/r/20210714182847.50360-9-don.brace@microchip.comReviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Signed-off-by: Mike McGowen <mike.mcgowen@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>