drm/i915: Add a platform independent way to check for CCS AUX planes

Future platforms change the location of CCS AUX planes in CCS
framebuffers, so add intel_fb_is_ccs_aux_plane() to query for these
planes independently of the platform. This function can be used
everywhere instead of is_ccs_plane() (or is_ccs_plane() && !cc_plane()),
since all the callers are only interested in CCS AUX planes (and not CCS
color-clear planes).

Add the corresponding intel_fb_is_gen12_ccs_aux_plane(), which can be
used everywhere instead of is_gen12_ccs_plane(), based on the above
explanation.

This change also unexports the is_gen12_ccs_modifier(),
is_gen12_ccs_plane(), is_gen12_ccs_cc_plane() functions as they are only
used in intel_fb.c

v1-v2: Unchanged
v3: (Ville)
- Use ccs_aux instead of the ccs_ctrl term everywhere.
- Use color_plane instead of plane term for FB plane indicies.
v4: Fix version range check. (Jani)

Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020195138.1841242-10-imre.deak@intel.com