arm64: dts: qcom: sm8350: Fix level triggered PMU interrupt polarity

As per interrupt documentation for SM8350 SoC, the polarity
for level triggered PMU interrupt is low, fix this.

Fixes: b7e8f433

 ("arm64: dts: qcom: Add basic devicetree support for SM8350 SoC")
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Link: https://lore.kernel.org/r/ca57409198477f7815e32a6a7467dcdc9b93dc4f.1613468366.git.saiprakash.ranjan@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>