ARM: dts: imx: ventana: add canbus support for GW52xx

The GW52xx baseboard supports CANbus so we enable it, configure its pinmux
and CAN_STBY gpio.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>