ARM: dts: msm: add spc sequence to cores

Spm driver is expecting both spc and pc from dts file as it
differentiates both. Add spc to cores spm.
Add command to perform explicit rpm communication.

Change-Id: Ib9b9d2304dba2d0f6bb29909943d466b5b346688
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>
Signed-off-by: Sridhar Gujje <sgujje@codeaurora.org>
Signed-off-by: Bharat Pawar <bpawar@codeaurora.org>
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>