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/bfin_mac.c b/drivers/net/bfin_mac.c
index e691bdf..36d4046 100644
--- a/drivers/net/bfin_mac.c
+++ b/drivers/net/bfin_mac.c
@@ -71,7 +71,7 @@
 	return 0;
 }
 
-static int bfin_miiphy_read(char *devname, uchar addr, uchar reg, ushort *val)
+static int bfin_miiphy_read(const char *devname, uchar addr, uchar reg, ushort *val)
 {
 	if (bfin_miiphy_wait())
 		return 1;
@@ -82,7 +82,7 @@
 	return 0;
 }
 
-static int bfin_miiphy_write(char *devname, uchar addr, uchar reg, ushort val)
+static int bfin_miiphy_write(const char *devname, uchar addr, uchar reg, ushort val)
 {
 	if (bfin_miiphy_wait())
 		return 1;