drm/i915: Add CCS capability for sprites

Allow sprites to scan out compressed framebuffers.

Since different platforms have a different set of planes that
support CCS let's add a small helper to determine whether a
specific plane supports CCS or not. Currently that information
is spread around in many places, and not all the pieces of
code even agree with each other.

In addition to allowing sprites to scan out compressed fbs,
the other fix here is that we stop rejecting them on pipe C
on CNL.

Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Daniel Stone <daniels@collabora.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171222192231.17981-6-ville.syrjala@linux.intel.com
Reviewed-by: Mika Kahola <mika.kahola@intel.com>