[media] s5p-mfc: Fix REQBUFS(0) for encoder

Handle REQBUFS(0) for CAPTURE queue as well. Also use the proper queue to call
it on for OUTPUT.

Signed-off-by: Pawel Osciak <posciak@chromium.org>
Signed-off-by: Kiran AVND <avnd.kiran@samsung.com>
Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>