ARM: dts: msm: Add rpm notification bit support

New targets have a SLP_CMD_MODE that could be set for rpm
notification. Add this bit for these targets and remove
rpm notification from spm sequence.

Change-Id: Idf3d26744dcf6a46ca978257f748b398fedba867
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>