arm64: dts: qcom: sdm845: Use the Low Power Island CX/MX for SLPI

The SLPI is powered by the Low Power Island power rails. Fix the incorrect
assignment.

Fixes: 74588aad

 ("arm64: dts: qcom: sdm845: add SLPI remoteproc")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20231220-topic-sdm845_slpi_lcxmx-v1-1-db7c72ef99ae@linaro.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>