Document R-Car V4H (R8A779G0), and R-Car Gen4 SoC bindings.

Link: https://lore.kernel.org/r/87zga6t5r4.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87pmau5ejk.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>