ARM: dts: i.MX27: Configure GPIOs as "input" by default

This patch changes the default direction for pins used
as GPIO to "input". This prevents a short circuit on the
configuration stage when GPIO-pin is connected to the
other output pin.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>