lpfc: Refactor Send LS Request support

Currently, the ability to send an NVME LS request is limited to the nvme
(host) side of the driver.  In preparation of both the nvme and nvmet sides
support Send LS Request, rework the existing send ls_req and ls_req
completion routines such that there is common code that can be used by
both sides.

Signed-off-by: Paul Ely <paul.ely@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>