[media] s5p-mfc: fix video device release double release in probe error path

Fix Decoder and encoder video device double release in probe error path.
video_device_release(dev->vfd_dec) get called twice if decoder register
fails. Also, video_device_release(dev->vfd_enc) get called twice if encoder
register fails.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>