Revert "ARM: dts: msm8974: Allow power collapse as minimum l2 gdhs mode"

This reverts commit 616e8a072e3a00c4b8b052b1338bfb3ea439b366.
Revert "msm: lpm_levels: remove rpm handshake in l2_gdhs mode"

This reverts commit 6e439ba1aaf4e344e4372e1ce69a1a95762a4266.