Warning messages when NVME_TARGET_FC not defined on ppc builds

The lpfc_nvmet_replenish_context() function is only meaningful when NVME
target mode enabled. Surround the function body with ifdefs for target
mode enablement.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>