arm64: dts: renesas: rcar-gen3: Add missing CMT nodes

Add device nodes for the Compare Match Timer (CMT) on the Renesas R-Car
M3-W+ (r8a77961) and D3 (r8a77995) SoCs.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20201209200738.811173-2-niklas.soderlund+renesas@ragnatech.se


[geert: squashed two commits]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>