clk: renesas: r8a779a0: Add TSC clock

Implement support for the TSC clock on V3U.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20210309165538.2682268-1-niklas.soderlund+renesas@ragnatech.se


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>