We can handle the surface alignment of CCS and UV color planes for all
modifiers at one place, so do this. An AUX color plane can be a CCS or a
UV plane, use only the more specific query functions and remove
is_aux_plane() becoming redundant.

While at it add a TODO for linear UV color plane alignments. The spec
requires this to be stride-in-bytes * 64 on all platforms, whereas the
driver uses an alignment of 4k for gen<12 and 256k for gen>=12 for
linear UV planes.

v2:
- Restore previous alignment for linear UV surfaces.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210421173220.3587009-1-imre.deak@intel.com