USB: typec: ucsi_ccg: convert i2c driver to use dev_groups

USB: typec: ucsi_ccg: convert i2c driver to use dev_groups

The driver core now supports the option to automatically create and
remove any needed sysfs attribute files for a driver when the device is
bound/removed from it.  Convert the uscsi_ccg code to use that instead
of trying to create sysfs files "by hand".

Cc: Ajay Gupta <ajayg@nvidia.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20190805193636.25560-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>