drm/i915/dp: only use training pattern 3 on platforms that support it

Ivybridge + 30" monitor prints a drm error on every modeset, since IVB
doesn't support DP3 we should even bother trying to use it.

This regression has been introduced in

commit 06ea66b6bb445043dc25a9626254d5c130093199
Author: Todd Previte <[e-mail]>
Date: Mon Jan 20 10:19:39 2014 -0700

drm/i915: Enable 5.4Ghz (HBR2) link rate for Displayport 1.2-capable
devices

Reported-by: Dave Airlie <[e-mail]>
Reference: http://mid.gmane.org/[e-mail]
Cc: Todd Previte <[e-mail]>
Cc: [e-mail] (3.15+)
Reviewed-by: Ville Syrjälä <[e-mail]>
Signed-off-by: Jani Nikula <[e-mail]>

drivers/gpu/drm/i915/intel_dp.c

···
 		}
 	}
 
-	/* Training Pattern 3 support */
+	/* Training Pattern 3 support, both source and sink */
 	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x12 &&
-	    intel_dp->dpcd[DP_MAX_LANE_COUNT] & DP_TPS3_SUPPORTED) {
+	    intel_dp->dpcd[DP_MAX_LANE_COUNT] & DP_TPS3_SUPPORTED &&
+	    (IS_HASWELL(dev_priv) || INTEL_INFO(dev_priv)->gen >= 8)) {
 		intel_dp->use_tps3 = true;
 		DRM_DEBUG_KMS("Displayport TPS3 supported\n");
 	} else