drm/i915/xelpd: Required bandwidth increases when VT-d is active

If VT-d is active, the memory bandwidth usage of the display is 5%
higher.  Take this into account when determining whether we can support
a display configuration.

Bspec: 64631
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210512042144.2089071-5-matthew.d.roper@intel.com

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

@@ -344,6 +344,9 @@ static unsigned int intel_bw_data_rate(struct drm_i915_private *dev_priv,
 	for_each_pipe(dev_priv, pipe)
 		data_rate += bw_state->data_rate[pipe];
 
+	if (DISPLAY_VER(dev_priv) >= 13 && intel_vtd_active())
+		data_rate = data_rate * 105 / 100;
+
 	return data_rate;
 }