ofnode: Replace of_n_addr_cells with of_n_size_cells

The size should be decoded using of_n_size_cells(), make it so.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>