Fix MAC address byte ordering in the uniq field

The UNIQ field can be used in the driver to detect duplicate devices.
For example, if a controller is connected via both Bluetooth and USB,
the driver can use the UNIQ field, which typically contains the unique
MAC address to identify that it's the same device.

Test: Connect a Bluetooth device and check its MAC address using
      ioctl(EVIOCGUNIQ) call.
Change-Id: I458608e845fcb24c0d615f6aef8d92ccb08d08ec