drm/i915: Add missing vbt check.

Let's respect vbt full_link (link_standby) on source side as well.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_psr.c

@@ -226,7 +226,7 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
 			       dev_priv->vbt.psr.idle_frames + 1 : 2;
 	uint32_t val = 0x0;
 	const uint32_t link_entry_time = EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
-	bool only_standby = false;
+	bool only_standby = dev_priv->vbt.psr.full_link;
 
 	if (IS_BROADWELL(dev) && dig_port->port != PORT_A)
 		only_standby = true;