arm64: dts: allwinner: h6: Add Hantro G2 node

H6 SoC has a second VPU, dedicated to VP9 decoding. It's a slightly
older design, though.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211129182633.480021-10-jernej.skrabec@gmail.com