ARM: orion: remove no longer needed DT IRQ code

Following the move of the Orion5x Device Tree support to use
irqchip_init() for the interrupt controller probing, the
plat-orion/irq.c code for DT-probing of the interrupt controller is no
longer necessary, so we can get rid of it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Link: https://lkml.kernel.org/r/1398202002-28530-38-git-send-email-thomas.petazzoni@free-electrons.com


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