scsi: ibmvfc: Define Sub-CRQ interrupt handler routine

Simple handler that calls Sub-CRQ drain routine directly.

Link: https://lore.kernel.org/r/20210114203148.246656-11-tyreld@linux.ibm.com


Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>