The board support is likely copied from the freescale-mx6-sabrelite,
which requires some GPIOs setup before Ethernet is usable. There is no
GPIOs used in this board's code, so remove the comment and along it the
<gpio.h> header.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>