drm/i915: Add functions to check for RC CCS CC and MC CCS modifiers

Instead of open-coding the checks add functions for this, simplifying
the handling of CCS modifiers on future platforms.

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/20211020195138.1841242-12-imre.deak@intel.com