HID: nintendo: set controller uniq to MAC

This patch sets the input device's uniq identifier to the controller's
MAC address. This is useful for future association between an IMU input
device with the normal input device as well as associating the
controller with any serial joy-con driver.

Signed-off-by: Daniel J. Ogorchock <djogorchock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>