net: dsa: constify probed name

Change the dsa_switch_driver.probe function to return a const char *.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
index 7a5f0ef..448deb5 100644
--- a/drivers/net/dsa/bcm_sf2.c
+++ b/drivers/net/dsa/bcm_sf2.c
@@ -135,9 +135,9 @@
 	return BCM_SF2_STATS_SIZE;
 }
 
-static char *bcm_sf2_sw_drv_probe(struct device *dsa_dev,
-				  struct device *host_dev,
-				  int sw_addr, void **_priv)
+static const char *bcm_sf2_sw_drv_probe(struct device *dsa_dev,
+					struct device *host_dev, int sw_addr,
+					void **_priv)
 {
 	struct bcm_sf2_priv *priv;