s5p-mfc: end-of-stream handling in encoder bug fix

s5p-mfc: end-of-stream handling in encoder bug fix

<UPSTREAM MERGE NOT REQUIRED>

linux-media commit eb36209297b7aadbd3144c74cb79d35704c3086e
Original commit message as follows:

  In some circumstances after issuing the V4L2_ENC_CMD_STOP the application
  could freeze. This patch prevents this behavior.

  Signed-off-by: Kamil Debski <k.debski@samsung.com>
  Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
  Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
  Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Change-Id: I4c2befaedf39882c86b694ce30d25367449b1260
Signed-off-by: John Sheu <sheu@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/45101