colibri_imx6: clean-up and migrate gpios to using driver model

colibri_imx6: clean-up and migrate gpios to using driver model

Migrate GPIOs to using driver model, properly request backlight, MMC/SD
card detect and USB power enable GPIOs and also enable SION bit in pin
muxing for auxiliary, backlight and USB power enable GPIOs.

While at it also update copyright year, clean-up/re-order includes, add
some comments clarifying ifdef scope and do some white-space clean-up.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>