apalis_imx6: clean-up and migrate gpios to using driver model

apalis_imx6: clean-up and migrate gpios to using driver model

Migrate GPIOs to using driver model, properly request backlight,
Ethernet PHY reset, MMC/SD card detect and USB power GPIOs and also
enable SION bit in pin muxing for Apalis, backlight, eMMC reset,
Ethernet PHY reset 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>