media: s5p-mfc: Use min scratch buffer size as provided by F/W

After MFC v8.0, mfc f/w lets the driver know how much scratch buffer
size is required for decoder. If mfc f/w has the functionality,
E_MIN_SCRATCH_BUFFER_SIZE, driver can know how much scratch buffer size
is required for encoder too.

Signed-off-by: Smitha T Murthy <smitha.t@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>