usb: typec: fix an IS_ERR() vs NULL bug in hd3ss3220_probe()

The device_get_named_child_node() function doesn't return error
pointers, it returns NULL on error.

Fixes: 1c48c759 ("usb: typec: driver for TI HD3SS3220 USB Type-C DRP port controller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20191011185055.GA20972@mwanda


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>