arm64: dts: renesas: r8a779g0: Add PWM device nodes

Add device nodes for the PWM timers on the Renesas R-Car V4H (R8A779G0)
SoC.

Signed-off-by: CongDang <cong.dang.xn@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/6a2df8c9f751993ae40aa8f196f4124e384b0aab.1665156417.git.geert+renesas@glider.be