drm/i915: Use BUG() in a case of a programming error

The port number should always be correctly set. Do the same thing as the
switch above and use BUG() to signal that branch is not supposed to be
taken.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -2836,8 +2836,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 		name = "DPDDC-D";
 		break;
 	default:
-		WARN(1, "Invalid port %c\n", port_name(port));
-		break;
+		BUG();
 	}
 
 	if (is_edp(intel_dp))