scsi: lpfc: Enable common send_io interface for SCSI and NVMe

To set up common use by the SCSI and NVMe I/O paths, create a new routine
that issues FCP I/O commands which can be used by either protocol.  The new
routine addresses SLI-3 vs SLI-4 differences within its implementation.

Replace the (SLI-3 centric) iocb routine in the SCSI path with this new
WQE-centric common routine.

Link: https://lore.kernel.org/r/20201115192646.12977-13-james.smart@broadcom.com


Co-developed-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>