media: cx231xx: fail probe if i2c_add_adapter fails

While at it, change the type of the previously always-zero i2c_rc
member to int, matching the returned type from i2c_add_adapter.
Signed-off-by: NPeter Rosin <peda@axentia.se>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/usb/cx231xx/cx231xx-i2c.c

@@ -538,7 +538,7 @@ int cx231xx_i2c_register(struct cx231xx_i2c *bus)
 
 	bus->i2c_adap.algo_data = bus;
 	i2c_set_adapdata(&bus->i2c_adap, &dev->v4l2_dev);
-	i2c_add_adapter(&bus->i2c_adap);
+	bus->i2c_rc = i2c_add_adapter(&bus->i2c_adap);
 
 	if (0 != bus->i2c_rc)
 		dev_warn(dev->dev,

drivers/media/usb/cx231xx/cx231xx.h

@@ -476,7 +476,7 @@ struct cx231xx_i2c {
 
 	/* i2c i/o */
 	struct i2c_adapter i2c_adap;
-	u32 i2c_rc;
+	int i2c_rc;
 
 	/* different settings for each bus */
 	u8 i2c_period;