drm/i915: Use {active,scaled}_planes to compute ilk watermarks

Use the {active,scaled}_planes bitmasks from the crtc state
rather than poking at the plane state directly. One step
towards eliminating the last use of the somewhat questionble
intel_atomic_crtc_state_for_each_plane_state() macro which
peeks into the plane state without actually holding the plane
mutex.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220211090629.15555-5-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>