scsi: ibmvfc: Treat H_CLOSED as success during sub-CRQ registration

A non-zero return code for H_REG_SUB_CRQ is currently treated as a failure
resulting in failing sub-CRQ setup. The case of H_CLOSED should not be
treated as a failure. This return code translates to a successful sub-CRQ
registration by the hypervisor, and is meant to communicate back that there
is currently no partner VIOS CRQ connection established as of yet. This is
a common occurrence during a disconnect where the client adapter can
possibly come back up prior to the partner adapter.

For non-zero return code from H_REG_SUB_CRQ treat a H_CLOSED as success so
that sub-CRQs are successfully setup.

Link: https://lore.kernel.org/r/20210302230543.9905-4-tyreld@linux.ibm.com
Fixes: 3034ebe2

 ("scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels")
Reviewed-by: Brian King <brking@linux.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>