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/core/dev.c b/net/core/dev.c
index b65a505..1421dad 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3124,8 +3124,7 @@
 	}
 
 	if (map) {
-		tcpu = map->cpus[((u64) hash * map->len) >> 32];
-
+		tcpu = map->cpus[reciprocal_scale(hash, map->len)];
 		if (cpu_online(tcpu)) {
 			cpu = tcpu;
 			goto done;