ARM: dts: sun8i: R40: Upgrade GICC reg size to 8K

The GIC used in the R40 SoC is an ARM GIC-400 with virtualization support,
so let's advertise the full 8K region of the GICC MMIO frame to enable
KVM's usage of the GIC (as we do already for all other SoCs).

Tested by running KVM on a Bananapi M2 Berry.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>