arm64: dts: renesas: r8a779g0: Add TPU device node

Add a device node for the 16-Bit Timer Pulse Unit (TPU) 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>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/b98acb22fdd1bcc6a9ca8a4255f85e04c571975c.1665156417.git.geert+renesas@glider.be