net: dsa: return directly from dsa_to_port

Return directly from within the loop as soon as the port is found,
otherwise we won't return NULL if the end of the list is reached.

Fixes: b96ddf25 ("net: dsa: use ports list in dsa_to_port")
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -283,13 +283,13 @@ struct dsa_switch {
 static inline struct dsa_port *dsa_to_port(struct dsa_switch *ds, int p)
 {
 	struct dsa_switch_tree *dst = ds->dst;
-	struct dsa_port *dp = NULL;
+	struct dsa_port *dp;
 
 	list_for_each_entry(dp, &dst->ports, list)
 		if (dp->ds == ds && dp->index == p)
-			break;
+			return dp;
 
-	return dp;
+	return NULL;
 }
 
 static inline bool dsa_is_unused_port(struct dsa_switch *ds, int p)