uboot-mediatek: fix build on Mac OS X

Copy patch added to uboot-sunxi by commit 3cc57ba462
("uboot-sunxi: add missing type __u64") also to uboot-mediatek.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/boot/uboot-mediatek/patches/260-add-missing-type-u64.patch

@@ -0,0 +1,10 @@
+--- a/include/linux/types.h
++++ b/include/linux/types.h
+@@ -1,6 +1,7 @@
+ #ifndef _LINUX_TYPES_H
+ #define _LINUX_TYPES_H
+ 
++typedef unsigned long long __u64;
+ #include <linux/posix_types.h>
+ #include <asm/types.h>
+ #include <stdbool.h>