drm/i915: Skip some bw_state readout on pre-icl

We only compute bw_state->data_rate and bw_state->num_active_planes
on icl+. Do the same during readout so that we don't leave random
junk inside the state.

v2: Skip the whole intel_bw_crtc_update() (Vinod)

Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306163420.3961-13-ville.syrjala@linux.intel.com

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_bw.c

@@ -1441,7 +1441,8 @@ void intel_bw_update_hw_state(struct intel_display *display)
 		if (crtc_state->hw.active)
 			bw_state->active_pipes |= BIT(pipe);
 
-		intel_bw_crtc_update(bw_state, crtc_state);
+		if (DISPLAY_VER(display) >= 11)
+			intel_bw_crtc_update(bw_state, crtc_state);
 	}
 }