msm: cpu_ops: set core SPM address to clock gating

For 64 bit target in the hotplug exit path the core SPM
address is not getting reset to default clock gating mode.
If this is not set to clock gating mode when the core enters
simple WFI mode it would execute the power collapse sequence
instead of clock gating sequence. This causes stability issues.

Change-Id: I9f8381625e347020a10466c713972d101c63bd44
Signed-off-by: Venkat Devarasetty <vdevaras@codeaurora.org>