ARM: dts: sunxi: h3/h5: Add r_intc node

The H3 and H5 SoCs have an additional interrupt controller in the RTC
power domain that can be used to enable wakeup for certain IRQs.

Add a node for it.

Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>