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/arch/arm/cpu/arm920t/at91rm9200/ether.c b/arch/arm/cpu/arm920t/at91rm9200/ether.c
index 91eab95..e1cdeba 100644
--- a/arch/arm/cpu/arm920t/at91rm9200/ether.c
+++ b/arch/arm/cpu/arm920t/at91rm9200/ether.c
@@ -283,7 +283,7 @@
 };
 
 #if defined(CONFIG_MII) || defined(CONFIG_CMD_MII)
-int  at91rm9200_miiphy_read(char *devname, unsigned char addr,
+int  at91rm9200_miiphy_read(const char *devname, unsigned char addr,
 		unsigned char reg, unsigned short * value)
 {
 	at91rm9200_EmacEnableMDIO (p_mac);
@@ -292,7 +292,7 @@
 	return 0;
 }
 
-int  at91rm9200_miiphy_write(char *devname, unsigned char addr,
+int  at91rm9200_miiphy_write(const char *devname, unsigned char addr,
 		unsigned char reg, unsigned short value)
 {
 	at91rm9200_EmacEnableMDIO (p_mac);