[media] s5p-mfc: fix state check from encoder queue_setup

MFCINST_GOT_INST state is set to encoder context with set_format
only for capture buffer. In queue_setup of encoder called during
reqbufs, it is checked MFCINST_GOT_INST state for both capture
and output buffer. So this patch fixes encoder to check
MFCINST_GOT_INST state only for capture buffer from queue_setup.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>