msm: mhi_dev: Release wakelock after sending completion

After the device receives a M3 event it updates the channel
state field on the host to suspend and releases the wakelock
before sending the M3 completion and can cause the system
to suspend before sending the M3 completion. Update to release
the wakelock after completing the M3 request to MHI and IPA MHI.

Change-Id: I084778805f5219a51045f093ddc71b3cecefede2
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>