Document SoC specific bindings for RZ/G2M (r8a774a1) SoC.
Signed-off-by: NBiju Das <biju.das@bp.renesas.com>
Reviewed-by: NSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>