ARM: dts: imx7d-pico-pi: Extend peripherals support

This adds following peripherals for the imx7d-pico-pi as:

 - LED
 - Touchscreen
 - GPIO

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>