Since we now have a gpiolib driver, remove this code:

The gpio-etraxfs driver (along with things like gpio-keys-polled for
polling support) replaces the GIO driver implementations in mach-a3 and
mach-fs.  The various generic external chip drivers replace the "virtual
gpio" parts.

The generic gpio-leds driver replaces the LED handling.
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NJesper Nilsson <jespern@axis.com>

Adds gpio and nandflash handling for Artpec-3.