irqchip/gic: Add arm,pl390 support

Add support for the PrimeCell® Generic Interrupt Controller (PL390) to
the GIC DT bindings and driver.

Currently the GIC driver treats this GIC variant the same as other GIC
variants, but there are differences in hardware topology (e.g. clock
inputs).

Sort the list of compatible values while we're at it.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh+dt@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Link: http://lkml.kernel.org/r/1442261204-30931-2-git-send-email-geert%2Brenesas@glider.be


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>