usb: typec: Remove retimers properly

Retimer device class is left dangling when the typec module
is unloaded. Attempts to reload the module failed with warning:

        "sysfs: cannot create duplicate filename '/class/retimer'"

Fixing the issue by unregistering the class properly.

Fixes: ddaf8d96

 ("usb: typec: Add support for retimers")
Reviewed-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20220825140411.10743-1-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>