scsi: lpfc: lpfc_scsi: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Notice that, in this particular case, I replaced "Drop thru" with
"fall through" annotations, which is what GCC is expecting to find.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

drivers/scsi/lpfc/lpfc_scsi.c

@@ -1137,7 +1137,7 @@ lpfc_bg_err_inject(struct lpfc_hba *phba, struct scsi_cmnd *sc,
 
 					break;
 				}
-				/* Drop thru */
+				/* fall through */
 			case SCSI_PROT_WRITE_INSERT:
 				/*
 				 * For WRITE_INSERT, force the error
@@ -1256,7 +1256,7 @@ lpfc_bg_err_inject(struct lpfc_hba *phba, struct scsi_cmnd *sc,
 					rc = BG_ERR_TGT | BG_ERR_CHECK;
 					break;
 				}
-				/* Drop thru */
+				/* fall through */
 			case SCSI_PROT_WRITE_INSERT:
 				/*
 				 * For WRITE_INSERT, force the
@@ -1338,7 +1338,7 @@ lpfc_bg_err_inject(struct lpfc_hba *phba, struct scsi_cmnd *sc,
 			switch (op) {
 			case SCSI_PROT_WRITE_PASS:
 				rc = BG_ERR_CHECK;
-				/* Drop thru */
+				/* fall through */
 
 			case SCSI_PROT_WRITE_INSERT:
 				/*
@@ -3822,7 +3822,7 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
 					lpfc_cmd->cur_iocbq.sli4_lxritag,
 					0, 0);
 			}
-		/* else: fall through */
+			/* fall through */
 		default:
 			cmd->result = DID_ERROR << 16;
 			break;