net: hamradio: baycom_epp: Mark expected switch fall-through

Mark switch cases where we are expecting to fall through.

This patch fixes the following warning (Building: i386):

drivers/net/hamradio/baycom_epp.c: In function ‘transmit’:
drivers/net/hamradio/baycom_epp.c:491:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
    if (i) {
       ^
drivers/net/hamradio/baycom_epp.c:504:3: note: here
   default:  /* fall through */
   ^~~~~~~

Notice that, in this particular case, the code comment is
modified in accordance with what GCC is expecting to find.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hamradio/baycom_epp.c

@@ -500,8 +500,9 @@ static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
 				}
 				break;
 			}
+			/* fall through */
 
-		default:  /* fall through */
+		default:
 			if (bc->hdlctx.calibrate <= 0)
 				return 0;
 			i = min_t(int, cnt, bc->hdlctx.calibrate);