core: return FDT_ADDR_T_NONE from devfdt_get_addr_[size_]name() on errors

core: return FDT_ADDR_T_NONE from devfdt_get_addr_[size_]name() on errors

Checking for the error cast to fdt_addr_t is rather awkward - IS_ERR()
can be used, but it's not really made to be used on fdt_addr_t, which
may not even be the same size as a native pointer.

Most places in U-Boot only check for FDT_ADDR_T_NONE; let's adjust the
error return to match the expectation.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Simon Glass <sjg@chromium.org>