With 'unevaluatedProperties' support implemented, there are a number of
warnings when running dtbs_check:

arch/arm64/boot/dts/renesas/r8a774b1-hihope-rzg2n-rev2-ex-idk-1110wr.dtb: spi@ee200000: Unevaluated properties are not allowed ('clock-names' was unexpected)
	From schema: Documentation/devicetree/bindings/memory-controllers/renesas,rpc-if.yaml

The main problem is that the DT bindings do not allow clock-names.
So just drop the clock-names properties from the SoC DTSI files.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20220829215128.5983-1-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>