net: use reciprocal_scale() helper

Replace open codings of (((u64) <x> * <y>) >> 32) with reciprocal_scale().

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/inet_hashtables.c

@@ -229,7 +229,7 @@ begin:
 			}
 		} else if (score == hiscore && reuseport) {
 			matches++;
-			if (((u64)phash * matches) >> 32 == 0)
+			if (reciprocal_scale(phash, matches) == 0)
 				result = sk;
 			phash = next_pseudo_random32(phash);
 		}