msm: vidc: Set extradata flag properly

Extradata flag is not set to output buffer header's flag in
case when a Mpeg2 clip is played and extenstion and user data
extradata is not enabled.
This change fixes the issue and set extradata flag properly
if extradata is enabled and extradata is available with the
the buffer.

CRs-fixed: 490067
Change-Id: I029dadb17d98dd37388eee34f51bd0dfaf56d14a
Signed-off-by: Deepak Verma <dverma@codeaurora.org>