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.

CRs-fixed: 406950
Change-Id: I094c0cb46906873092044ee64fc1f1299df7a426
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>