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>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 4836af8..25ffe73 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -243,7 +243,7 @@
 				goto exact_match;
 		} else if (score == badness && reuseport) {
 			matches++;
-			if (((u64)hash * matches) >> 32 == 0)
+			if (reciprocal_scale(hash, matches) == 0)
 				result = sk;
 			hash = next_pseudo_random32(hash);
 		}
@@ -323,7 +323,7 @@
 			}
 		} else if (score == badness && reuseport) {
 			matches++;
-			if (((u64)hash * matches) >> 32 == 0)
+			if (reciprocal_scale(hash, matches) == 0)
 				result = sk;
 			hash = next_pseudo_random32(hash);
 		}