drm/i915: WARN for eDP encoders in intel_dp_detect_dpcd()

We are not calling this function for eDP, so add an early assert about
this for clarity.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190509173446.31095-7-imre.deak@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -4844,15 +4844,15 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
 	u8 *dpcd = intel_dp->dpcd;
 	u8 type;
 
+	if (WARN_ON(intel_dp_is_edp(intel_dp)))
+		return connector_status_connected;
+
 	if (lspcon->active)
 		lspcon_resume(lspcon);
 
 	if (!intel_dp_get_dpcd(intel_dp))
 		return connector_status_disconnected;
 
-	if (intel_dp_is_edp(intel_dp))
-		return connector_status_connected;
-
 	/* if there's no downstream port, we're done */
 	if (!drm_dp_is_branch(dpcd))
 		return connector_status_connected;