miiphy: constify device name

The driver name does not need to be writable, so constify it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index 6b801ce..2d4ffed 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -62,7 +62,7 @@
 /*
  * MII-interface related functions
  */
-static int fec_miiphy_read(char *dev, uint8_t phyAddr, uint8_t regAddr,
+static int fec_miiphy_read(const char *dev, uint8_t phyAddr, uint8_t regAddr,
 		uint16_t *retVal)
 {
 	struct eth_device *edev = eth_get_dev_by_name(dev);
@@ -119,7 +119,7 @@
 	debug("fec_init: mii_speed %#lx\n",
 			fec->eth->mii_speed);
 }
-static int fec_miiphy_write(char *dev, uint8_t phyAddr, uint8_t regAddr,
+static int fec_miiphy_write(const char *dev, uint8_t phyAddr, uint8_t regAddr,
 		uint16_t data)
 {
 	struct eth_device *edev = eth_get_dev_by_name(dev);