common: Move mii_init() function out of common.h

This function belongs in mii.h so move it over.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/net/mcfmii.c b/drivers/net/mcfmii.c
index 961618b..b8af2cc 100644
--- a/drivers/net/mcfmii.c
+++ b/drivers/net/mcfmii.c
@@ -15,6 +15,7 @@
 #include <asm/fec.h>
 #endif
 #include <asm/immap.h>
+#include <linux/mii.h>
 
 DECLARE_GLOBAL_DATA_PTR;