Starting with R-Car H3 ES2.0, the parent of RCLK is selected using MD28.

Add support for that, but retain the old behavior for R-Car H3 ES1.x and
M3-W ES1.0 using a quirk.

Inspired by a patch by Takeshi Kihara in the BSP.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Takeshi Kihara <takeshi.kihara.df@renesas.com>