Currently, this is only defined in arch/arm/include/asm/types.h,
so move it to include/linux/types.h to make it available for all
architectures.

I defined it with phys_addr_t as Linux does.  I needed to surround
the define with #ifdef __KERNEL__ ... #endif to avoid build errors
in tools building.  (Host tools should not include <linux/types.h>
in the first place, but this is already messy in U-Boot...)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>