Add mii_init() prototype

to get rid of a *lot* of compiler warnings.
Signed-off-by: NWolfgang Denk <wd@denx.de>

include/common.h

@@ -565,7 +565,7 @@ ulong	bootcount_load (void);
 #define BOOTCOUNT_MAGIC		0xB001C041
 
 /* $(CPU)/.../<eth> */
-/*void mii_init (void);*/
+void mii_init (void);
 
 /* $(CPU)/.../lcd.c */
 ulong	lcd_setmem (ulong);