clk: renesas: r8a779g0: Add SYS-DMAC clocks

Add the module clocks used by the Direct Memory Access Controllers for
System (SYS-DMAC) on the Renesas R-Car V4H (R8A779G0) SoC.

Extracted from a larger patch in the BSP by Kazuya Mizuguchi.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/d9f8322d362c7cebb29bfa7e128b4974882c4a7d.1664204336.git.geert+renesas@glider.be