msm: ipa: fix TAG process timeout

In case of timeout in TAG process, completion object was referenced
after it got free. This commit adds reference count to the completion
object to avoid this condition.

Change-Id: I059813fe26b39b3fe60adadd9fa90397304219bc
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Ravit Katzav <rkatzav@codeaurora.org>