ARM: dts: imx6-colibri: Add missing pinmuxing to Toradex eval board

This patch adds some missing pinmuxing that is in the colibri
standard to the dts.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>