drm/i2c: tda998x: check the CEC device creation

This patch checks if the CEC device is well created at intialization
time.
Tested-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NJean-Francois Moine <moinejf@free.fr>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

drivers/gpu/drm/i2c/tda998x_drv.c

@@ -1144,6 +1144,8 @@ tda998x_encoder_init(struct i2c_client *client,
 
 	priv->current_page = 0;
 	priv->cec = i2c_new_dummy(client->adapter, 0x34);
+	if (!priv->cec)
+		return -ENODEV;
 	priv->dpms = DRM_MODE_DPMS_OFF;
 
 	encoder_slave->slave_priv = priv;