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/ns7520_eth.c b/drivers/net/ns7520_eth.c
index c28726e..bfa651b 100644
--- a/drivers/net/ns7520_eth.c
+++ b/drivers/net/ns7520_eth.c
@@ -761,7 +761,7 @@
 /**
  * Read a 16-bit value from an MII register.
  */
-extern int ns7520_miiphy_read(char *devname, unsigned char const addr,
+extern int ns7520_miiphy_read(const char *devname, unsigned char const addr,
 		unsigned char const reg, unsigned short *const value)
 {
 	int ret = MII_STATUS_FAILURE;
@@ -807,7 +807,7 @@
 /**
  * Write a 16-bit value to an MII register.
  */
-extern int ns7520_miiphy_write(char *devname, unsigned char const addr,
+extern int ns7520_miiphy_write(const char *devname, unsigned char const addr,
 		unsigned char const reg, unsigned short const value)
 {
 	int ret = MII_STATUS_FAILURE;