net: dsa: mv88e6xxx: Fix -Wformat-security warnings

We are not specifying an explicit format argument but instead passing a
string litteral which causes these two warnings to show up:

drivers/net/dsa/mv88e6xxx/chip.c: In function
'mv88e6xxx_irq_poll_setup':
drivers/net/dsa/mv88e6xxx/chip.c:483:2: warning: format not a string
literal and no format arguments [-Wformat-security]
  chip->kworker = kthread_create_worker(0, dev_name(chip->dev));
  ^~~~
drivers/net/dsa/mv88e6xxx/ptp.c: In function 'mv88e6xxx_ptp_setup':
drivers/net/dsa/mv88e6xxx/ptp.c:403:4: warning: format not a string
literal and no format arguments [-Wformat-security]
    dev_name(chip->dev));
    ^~~~~~~~
  LD [M]  drivers/net/dsa/mv88e6xxx/mv88e6xxx.o
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -480,7 +480,7 @@ static int mv88e6xxx_irq_poll_setup(struct mv88e6xxx_chip *chip)
 	kthread_init_delayed_work(&chip->irq_poll_work,
 				  mv88e6xxx_irq_poll);
 
-	chip->kworker = kthread_create_worker(0, dev_name(chip->dev));
+	chip->kworker = kthread_create_worker(0, "%s", dev_name(chip->dev));
 	if (IS_ERR(chip->kworker))
 		return PTR_ERR(chip->kworker);
 

drivers/net/dsa/mv88e6xxx/ptp.c

@@ -400,7 +400,7 @@ int mv88e6xxx_ptp_setup(struct mv88e6xxx_chip *chip)
 
 	chip->ptp_clock_info.owner = THIS_MODULE;
 	snprintf(chip->ptp_clock_info.name, sizeof(chip->ptp_clock_info.name),
-		 dev_name(chip->dev));
+		 "%s", dev_name(chip->dev));
 	chip->ptp_clock_info.max_adj	= 1000000;
 
 	chip->ptp_clock_info.n_ext_ts	= ptp_ops->n_ext_ts;