scsi: ibmvfc: Map/request irq and register Sub-CRQ interrupt handler

Create an irq mapping for the hw_irq number provided from phyp firmware.
Request an irq assigned our Sub-CRQ interrupt handler. Unmap these irqs at
Sub-CRQ teardown.

Link: https://lore.kernel.org/r/20210114203148.246656-12-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>