msm: clock-pm: Introduce clock-pm specific driver

This patch introduces clock-pm driver, this is intended to
be used for pm specific clk handling during idle and
suspend power collapse.

Add support to register with cpu pm notification for
idle and suspend power collapse. Also, allow apss/bimc
sleep clock gating during idle power collapse.

Change-Id: Ifb9d635020b9f3e7d74b119f3aafc35b5339f751
Signed-off-by: Girish S Ghongdemath <girishsg@codeaurora.org>