drm/i915/mtl: Drop FLAT CCS check

Remove FLAT CCS check from XY_FAST_COLOR_BLT usage, thus
enabling MTL to use it.

Signed-off-by: Pallavi Mishra <pallavi.mishra@intel.com>
Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230505144005.23480-1-nirmoy.das@intel.com