ARM: mvebu: Use the ARMADA_370_XP_IRQ option

ARM: mvebu: Use the ARMADA_370_XP_IRQ option

Now that there is a ARMADA_370_XP_IRQ option to enable the irqchip
driver for Armada 370, XP, 375, 38x and 39x, let's select this option
when needed. Note that this selection is currently not mandatory
because ARMADA_370_XP_IRQ is for now always enabled when ARCH_MVEBU=y,
but this is something that we will change in the future, and therefore
we should make the relevant platforms select ARMADA_370_XP_IRQ when
needed.

Due to this, selecting GENERIC_IRQ_CHIP is no longer needed.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1455115621-22846-7-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>