[media] exynos-gsc: Use user configured colorspace if provided

Use colorspace provided by the user as we are only doing scaling and
color encoding conversion, we won't be able to transform the colorspace
itself and the colorspace won't mater in that operation.

Also always use output colorspace on the capture side.

If the user does not provide a colorspace do not make it up, we might
later while processing need to figure out the colorspace, which
is possible depending on the frame size but do not ever guess and
leak that guess to the userspace.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Thibault Saunier <thibault.saunier@osg.samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>