msm: spm: Replace smp_processor_id call with get_cpu

Spm_processor_id call results in warning message when
called with preempt enabled. Instead call get_cpu to get
the current cpu ID and enable preempt again because the
function further calls smp_call_function_single which
disables preempt within.

Change-Id: I246f26b023da97038c5d6b675a820f07ac62fda1
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>