arm64: dts: qcom: sdm845-db845c: drop SPI label

The SPI controller nodes do not use/allow label property:

  sdm845-db845c.dtb: spi@888000: Unevaluated properties are not allowed ('label' was unexpected)

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230308125906.236885-4-krzysztof.kozlowski@linaro.org