vidc: Fix EOS handling if video h/w has a frame in transaction

In case of video hardware is encoding a frame and EOS buffer with
with zero data length arrived, set the EOS flag to the transaction
available in the transaction table which will be passed to the
client in frame done callback from the video hardware.

Change-Id: I03862906be603ff769fb6aa0a2191a9ea87529ca
Signed-off-by: Deepak Verma <dverma@codeaurora.org>