ARM64: dts: marvell: armada-37xx: Fix GIC maintenance interrupt

commit 95696d292e204073433ed2ef3ff4d3d8f42a8248 upstream.

The GIC-500 integrated in the Armada-37xx SoCs is compliant with
the GICv3 architecture, and thus provides a maintenance interrupt
that is required for hypervisors to function correctly.

With the interrupt provided in the DT, KVM now works as it should.
Tested on an Espressobin system.

Fixes: adbc3695 ("arm64: dts: add the Marvell Armada 3700 family and a development board")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>