msm: vidc: removed the async v4l2 event for session unsupported

When an unsupported session is detected when handling an
information event, send only the unsupported event to client
and ignore the informational event.

CRs-fixed: 702914
Change-Id: Iede16ebf5b5f0216b18de71b8d3cbe669597188a
Signed-off-by: Jia Meng <jmeng@codeaurora.org>