[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.