scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels

Allocate a set of Sub-CRQs in advance. During channel setup the client and
VIOS negotiate the number of queues the VIOS supports and the number that
the client desires to request. Its possible that the final channel
resources allocated is less than requested, but the client is still
responsible for sending handles for every queue it is hoping for.

Also, provide deallocation cleanup routines.

Link: https://lore.kernel.org/r/20210114203148.246656-8-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>