clk: renesas: r8a7796: Add CMM clocks

Add clock definitions for CMM units on Renesas R-Car Gen3 M3-W.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>