scsi: qla2xxx: SAN congestion management implementation

scsi: qla2xxx: SAN congestion management implementation

* Firmware Initialization with SCM enabled based on NVRAM setting and
  firmware support (About Firmware).

* Enable PUREX and add support for fabric performance impact
  notification (FPIN) handling.

* Allocate a default PUREX item for each vha to handle memory allocation
  failures in ISR.

Link: https://lore.kernel.org/r/20200630102229.29660-3-njavali@marvell.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>