inet: Use fallthrough;

Convert the various uses of fallthrough comments to fallthrough;

Done via script
Link: https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/

And by hand:

net/ipv6/ip6_fib.c has a fallthrough comment outside of an #ifdef block
that causes gcc to emit a warning if converted in-place.

So move the new fallthrough; inside the containing #ifdef/#endif too.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 2931224..2430c2f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4370,7 +4370,7 @@ static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
 			IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 			break;
 		}
-		/* FALLTHROUGH */
+		fallthrough;
 	case IPSTATS_MIB_OUTNOROUTES:
 		IP6_INC_STATS(net, idev, ipstats_mib_noroutes);
 		break;