lpfc: Refactor NVME LS receive handling

In preparation for supporting both intiator mode and target mode
receiving NVME LS's, commonize the existing NVME LS request receive
handling found in the base driver and in the nvmet side.

Using the original lpfc_nvmet_unsol_ls_event() and
lpfc_nvme_unsol_ls_buffer() routines as a templates, commonize the
reception of an NVME LS request. The common routine will validate the LS
request, that it was received from a logged-in node, and allocate a
lpfc_async_xchg_ctx that is used to manage the LS request. The role of
the port is then inspected to determine which handler is to receive the
LS - nvme or nvmet. As such, the nvmet handler is tied back in. A handler
is created in nvme and is stubbed out.

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>