drm/i915/fb: Don't report MC CCS plane capability on GEN<12

Remove the MC CCS plane capability on GEN<12, since it's not present
there. This didn't cause a problem, since the display version check
filtered out the MC CCS modifiers before GEN12.

Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.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/20211026161517.2694067-2-imre.deak@intel.com