rpm-smd: Initialize the completion before smd_open call

Currently smd_open call happens before the completion event
initializations. We could run into spinlock bad magic issue if the
driver receives smd notification before initialization completes.
Therefore, initialize this during msm_rpm_data declaration.

Change-Id: Ia9b01a5717416d659b1308a693b1a3667a5a11b3
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>