msm: cvp: stop session queue when session closed

There is a chance CVP application closes a session without
stopping it first. The change will ensure there is no resource
leakage in above case.

Change-Id: I2b93af11a47eda8de81f3d8c0f054e3319e48802
Signed-off-by: George Shen <sqiao@codeaurora.org>