ARM: dts: msm: remove PMIC SW Mode support for msm8974Pro-AC

Remove references to PMIC SW Mode properties in msm8974pro-ac.dtsi
because the requirements to disable CX auto mode during thermal
condition is not needed.

Change-Id: I760652a47a4a1bb0e9687a1be64c4cc817239981
Signed-off-by: Jennifer Liu <chihning@codeaurora.org>