net: Add helper function to compare inetpeer addresses

tcp_metrics and inetpeer both have functions to compare inetpeer
addresses. Consolidate into 1 version.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 4ef4dd4..c8cbc2b 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -81,11 +81,7 @@
 static bool addr_same(const struct inetpeer_addr *a,
 		      const struct inetpeer_addr *b)
 {
-	if (a->family != b->family)
-		return false;
-	if (a->family == AF_INET)
-		return a->addr.a4 == b->addr.a4;
-	return ipv6_addr_equal(&a->addr.in6, &b->addr.in6);
+	return inetpeer_addr_cmp(a, b) == 0;
 }
 
 struct tcpm_hash_bucket {