Subordinate Command Response Queues (Sub CRQ) are used in conjunction with
the primary CRQ when more than one queue is needed by the virtual I/O
adapter. Recent phyp firmware versions support Sub CRQ's with ibmvfc
adapters. This feature is a prerequisite for supporting multiple hardware
backed submission queues in the vfc adapter.

The Sub CRQ command element differs from the standard CRQ in that it is
32bytes long as opposed to 16bytes for the latter. Despite this extra
16bytes the ibmvfc protocol will use the original CRQ command element
mapped to the first 16bytes of the Sub CRQ element initially.

Add definitions for the Sub CRQ command element and queue.

Link: https://lore.kernel.org/r/20210114203148.246656-7-tyreld@linux.ibm.comReviewed-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>