fdt: Change OF_BAD_ADDR to FDT_ADDR_T_NONE

Currently OF_BAD_ADDR is always -1ULL. When using OF_BAD_ADDR as the
return value of dev_get_addr(), it creates potential size mismatch
as dev_get_addr() uses FDT_ADDR_T_NONE as the return value which can
be either -1U or -1ULL depending on CONFIG_PHYS_64BIT. Now we change
OF_BAD_ADDR to FDT_ADDR_T_NONE to avoid such case.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>