scsi: qla2xxx: Add pci function reset support.

This patch provide call back functions to stop the chip and resume the chip
if the PCI lower level driver wants to perform function level reset/FLR.
Before the FLR, the chip will be stopped to turn off all DMA activity.
After the FLR, the chip is reset to resume previous operation state.

Signed-off-by: Quinn Tran <qtran@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>