msm: vidc: Remove init_completion before wait

On 4.9 kernel list is currupted while killing
video session. This could be because of session
abort, as session is rejected due to overload.

So, Removing init_completion before wait as this
is done during session init.

Change-Id: I4d75a119ddff0d1743ecddb1048e6289f2fbb027
Signed-off-by: Mansur Alisha Shaik <mansur@codeaurora.org>