ARM: dts: imx6-apalis: Add touchscreens used on Toradex eval boards

This commit adds the touchscreen from Toradex so one can enable it.
It is disabled by default because the pins are also used for PWM<B>,
PWM<C>, aka pwm2, pwm3 which is the standard use for colibri boards.

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>