clk: renesas: r8a779g0: Tidy up DMAC name on SYS-DMAC

"sydm" is a bit name. Let's rename it to the common "sys-dmac".

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87v8l3z3y8.wl-kuninori.morimoto.gx@renesas.com


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