clk: renesas: r9a06g032: Document structs

Add some kerneldoc comments for the structures.

Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230301215520.828455-4-ralph.siemsen@linaro.org


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>