drm/i915: Allow SSC parameter to override VBT value

Allow SSC to be enabled even when the BIOS disables it for testing SSC paths.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 04411ad..6039496 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4584,7 +4584,9 @@
 
 static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
 {
-	return dev_priv->lvds_use_ssc && i915_panel_use_ssc
+	if (i915_panel_use_ssc >= 0)
+		return i915_panel_use_ssc != 0;
+	return dev_priv->lvds_use_ssc
 		&& !(dev_priv->quirks & QUIRK_LVDS_SSC_DISABLE);
 }