ARM: orion: remove no longer needed gpio DT code

Following the move to pure DT-based probing of the GPIO controllers on
Orion5x, some code in plat-orion/orion-gpio.c can be removed as it is
no longer used.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Link: https://lkml.kernel.org/r/1398202002-28530-39-git-send-email-thomas.petazzoni@free-electrons.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>