arm64: dts: renesas: Fix thermal-sensors on single-zone sensors

"make dtbs_check":

    arch/arm64/boot/dts/renesas/r8a774c0-cat874.dtb: thermal-zones: cpu-thermal:thermal-sensors: [[74], [0]] is too long
    arch/arm64/boot/dts/renesas/r8a774c0-ek874.dtb: thermal-zones: cpu-thermal:thermal-sensors: [[79], [0]] is too long
    arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dtb: thermal-zones: cpu-thermal:thermal-sensors: [[82], [0]] is too long
    arch/arm64/boot/dts/renesas/r8a774c0-ek874-mipi-2.1.dtb: thermal-zones: cpu-thermal:thermal-sensors: [[87], [0]] is too long
    arch/arm64/boot/dts/renesas/r8a77990-ebisu.dtb: thermal-zones: cpu-thermal:thermal-sensors: [[105], [0]] is too long
	    From schema: Documentation/devicetree/bindings/thermal/thermal-zones.yaml

Indeed, the thermal sensors on R-Car E3 and RZ/G2E support only a single
zone, hence #thermal-sensor-cells = <0>.

Fix this by dropping the bogus zero cell from the thermal sensor
specifiers.

Fixes: 8fa7d18f ("arm64: dts: renesas: r8a77990: Create thermal zone to support IPA")
Fixes: 8438bfda ("arm64: dts: renesas: r8a774c0: Create thermal zone to support IPA")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/28b812fdd1fc3698311fac984ab8b91d3d655c1c.1655301684.git.geert+renesas@glider.be