scsi: lpfc: SLI path split: Refactor lpfc_iocbq

Currently, SLI3 and SLI4 data paths use the same lpfc_iocbq structure.
This is a "common" structure but many of the components refer to sli-rev
specific entities which can lead the developer astray as to what they
actually mean, should be set to, or when they should be used.

This first patch prepares the lpfc_iocbq structure so that elements common
to both SLI3 and SLI4 data paths are more appropriately named, making it
clear they apply generically.

Fieldnames based on 'iocb' (sli3) or 'wqe' (sli4) which are actually
generic to the paths are renamed to 'cmd':

 - iocb_flag is renamed to cmd_flag

 - lpfc_vmid_iocb_tag is renamed to lpfc_vmid_tag

 - fabric_iocb_cmpl is renamed to fabric_cmd_cmpl

 - wait_iocb_cmpl is renamed to wait_cmd_cmpl

 - iocb_cmpl and wqe_cmpl are combined and renamed to cmd_cmpl

 - rsvd2 member is renamed to num_bdes due to pre-existing usage

The structure name itself will retain the iocb reference as changing to a
more relevant "job" or "cmd" title induces many hundreds of line changes
for only a name change.

lpfc_post_buffer is also renamed to lpfc_sli3_post_buffer to indicate use
in the SLI3 path only.

Link: https://lore.kernel.org/r/20220225022308.16486-2-jsmart2021@gmail.com


Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>