arm: sun8i: h3: correct the GIC compatible in H3 to gic-400

According to the datasheets provided by Allwinner, both Allwinner H3 and
H5 use GIC-400 as their interrupt controller.

For better device tree reusing, correct the GIC compatible in H3 DTSI to
"arm,gic-400", thus this node can be reused in H5.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>