ARM: dts: imx: Pass empty memory size on board dts

In preparation for removing 'reg = <0 0>;' from the dtsi SoC files, pass
'reg = <0 0 >;' to the dts/dtsi board files that do not pass the memory
size.

Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>