arm64: dts: alpine: Fix GIC unit address

Node unit address should be the same as first address appearing in "reg"
property.  Fixes DTC warning:

    arch/arm64/boot/dts/al/alpine-v2.dtsi:116.38-126.5:
        Warning (simple_bus_reg): /soc/interrupt-controller@f0100000: simple-bus unit address format error, expected "f0200000"

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>