ARM: dts: imx: emcon-avari: Fix nxp,pca8574 #gpio-cells

According to the DT bindings, #gpio-cells must be two.

Fixes: 63e71fed

 ("ARM: dts: Add support for emtrion emCON-MX6 series")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>