net: dsa: mv88e6xxx: fix boolreturn.cocci warnings

drivers/net/dsa/mv88e6xxx/serdes.c:66:9-10: WARNING: return of 0/1 in function 'mv88e6352_port_has_serdes' with return type bool

 Return statements in functions returning bool should use
 true/false instead of 1/0.
Generated by: scripts/coccinelle/misc/boolreturn.cocci

Fixes: eb755c3 ("net: dsa: mv88e6xxx: Add helper to determining if port has SERDES")
CC: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/serdes.c

@@ -63,15 +63,15 @@ static bool mv88e6352_port_has_serdes(struct mv88e6xxx_chip *chip, int port)
 	err = mv88e6xxx_port_get_cmode(chip, port, &cmode);
 	if (err) {
 		dev_err(chip->dev, "failed to read cmode\n");
-		return 0;
+		return false;
 	}
 
 	if ((cmode == MV88E6XXX_PORT_STS_CMODE_100BASE_X) ||
 	    (cmode == MV88E6XXX_PORT_STS_CMODE_1000BASE_X) ||
 	    (cmode == MV88E6XXX_PORT_STS_CMODE_SGMII))
-		return 1;
+		return true;
 
-	return 0;
+	return false;
 }
 
 int mv88e6352_serdes_power(struct mv88e6xxx_chip *chip, int port, bool on)