clk: renesas: r8a779g0: Add TPU clock

Add the module clock used by the 16-Bit Timer Pulse Unit (TPU) on the
Renesas R-Car V4H (R8A779G0) SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/f2c1e2c5411b7bd6af726e6baf6e1efc354a7cdf.1665147497.git.geert+renesas@glider.be