selftests: forwarding: Add MAC get helper

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/tools/testing/selftests/net/forwarding/lib.sh b/tools/testing/selftests/net/forwarding/lib.sh
index 92e4642..083a16e 100644
--- a/tools/testing/selftests/net/forwarding/lib.sh
+++ b/tools/testing/selftests/net/forwarding/lib.sh
@@ -270,6 +270,13 @@
        ip -j -s link show dev $if_name | jq '.[]["stats64"]["tx"]["packets"]'
 }
 
+mac_get()
+{
+	local if_name=$1
+
+	ip -j link show dev $if_name | jq -r '.[]["address"]'
+}
+
 bridge_ageing_time_get()
 {
 	local bridge=$1