ARM: dts: qcom: sdx55: Add pshold support

Add support for pshold block to drive pshold towards the PMIC, which is
used to trigger a configurable event such as reboot or poweroff of the
SDX55 platform.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20210118051005.55958-7-manivannan.sadhasivam@linaro.org


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