consolidate mdelay by providing a common function for all users

There are several mdelay() definitions in the driver and
board code. Remove them all and provide a common mdelay()
in lib/time.c.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>

include/common.h

@@ -706,6 +706,7 @@ int strcmp_compar(const void *, const void *);
 
 /* lib/time.c */
 void	udelay        (unsigned long);
+void mdelay(unsigned long);
 
 /* lib/uuid.c */
 void uuid_str_to_bin(const char *uuid, unsigned char *out);