ARM: dts: imx6ul-14x14-evk: Add LCD and backlight support

Add support for the LCD8000-43T display and for the backlight
controlled via PWM1.

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