irqchip: gic: Add binding probe for ARM GIC400

Commit 3ab72f91 "dt-bindings: add GIC-400 binding" added the
"arm,gic-400" compatible string, but the corresponding IRQCHIP_DECLARE
was never added to the gic driver.

Therefore add the missing irqchip declaration for it.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>

Removed additional empty line and adapted commit message to mark it
as fixing an issue.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Will Deacon <will.deacon@arm.com>
Fixes: 3ab72f91 ("dt-bindings: add GIC-400 binding")
Cc: <stable@vger.kernel.org> # v3.14+
Link: https://lkml.kernel.org/r/2621565.f5eISveXXJ@diego


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