scsi: st: mark expected switch fall-throughs

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

Addresses-Coverity-ID: 114994 ("Missing break in switch")
Addresses-Coverity-ID: 114995 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Acked-by: Kai Mäkisara <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/st.c

···
 		switch (sense[0] & 0x7f) {
 		case 0x71:
 			s->deferred = 1;
+			/* fall through */
 		case 0x70:
 			s->fixed_format = 1;
 			s->flags = sense[2] & 0xe0;
 			break;
 		case 0x73:
 			s->deferred = 1;
+			/* fall through */
 		case 0x72:
 			s->fixed_format = 0;
 			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
···
 	switch (cmd_in) {
 	case MTFSFM:
 		chg_eof = 0;	/* Changed from the FSF after this */
+		/* fall through */
 	case MTFSF:
 		cmd[0] = SPACE;
 		cmd[1] = 0x01;	/* Space FileMarks */
···
 		break;
 	case MTBSFM:
 		chg_eof = 0;	/* Changed from the FSF after this */
+		/* fall through */
 	case MTBSF:
 		cmd[0] = SPACE;
 		cmd[1] = 0x01;	/* Space FileMarks */