net: dsa: mv88e6xxx: Add missing initialization in mv88e6xxx_set_port_state()

drivers/net/dsa/mv88e6xxx.c: In function ‘mv88e6xxx_set_port_state’:
drivers/net/dsa/mv88e6xxx.c:905: warning: ‘ret’ may be used uninitialized in this function

If oldstate == state, mv88e6xxx_set_port_state() will return an
uninitialized value. Pre-initialize ret to zero to fix this.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -900,7 +900,7 @@ static int _mv88e6xxx_flush_fid(struct dsa_switch *ds, int fid)
 static int mv88e6xxx_set_port_state(struct dsa_switch *ds, int port, u8 state)
 {
 	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
-	int reg, ret;
+	int reg, ret = 0;
 	u8 oldstate;
 
 	mutex_lock(&ps->smi_mutex);