ARM: dts: msm: Remove RPM handshake from PC sequence for apq8084

Power collapse will not do RPM handshake anymore. Remove
that command from spm-pc sequence.

Change-Id: Ib2007d49a6a0ae9f102161d9857d8fa3abad73fb
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>