arm64: boot: dts: r8a774[a/b/e]1-beacon: Consolidate sound clocks

arm64: boot: dts: r8a774[a/b/e]1-beacon: Consolidate sound clocks

Each kit-level file represents a SOM + baseboard for a specific
SoC type and uses specific clocks unique to each SoC.  With the
exception of one clock, the rest of the clock info was duplicated.

There is a generic clock called CPG_AUDIO_CLK_I defined in each of
the SoC DTSI files which points to this unique clock. By using that,
the clock information for the rcar_sound can be consolidated into
the baseboard file and have it reference this generic clock thus
removing the duplication from the three variants.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230104141245.8407-4-aford173@gmail.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>