media: cx231xx: replace BUG_ON with recovery code

In cx231xx_i2c_register, if dev->cx231xx_send_usb_command is NULL,
the code crashes. However, the callers in cx231xx-core are able to
handle the error without crashing. This patch fixes this issue.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

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

@@ -515,7 +515,8 @@ int cx231xx_i2c_register(struct cx231xx_i2c *bus)
 {
 	struct cx231xx *dev = bus->dev;
 
-	BUG_ON(!dev->cx231xx_send_usb_command);
+	if (!dev->cx231xx_send_usb_command)
+		return -EINVAL;
 
 	bus->i2c_adap = cx231xx_adap_template;
 	bus->i2c_adap.dev.parent = dev->dev;