drivers: thermal: sdpm: Add SDPM clock notifier driver

Add SDPM clock notifier driver, which will register for clock rate
change notification and write the clock rate into SDPM CSR register. The
SDPM hardware will monitor the frequency changes and recommend
mitigation using policy engine.

Change-Id: I56b2941b3c3e47bdb49bf805a2fc9acd4356470f
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>