Package the Aquantia AQR PHY driver as kmod.
This enables using the Aquantia driver with hwmon support on targets where
hwmon is not compiled-in.
Currently, in case when AQR driver is compiled-in but hwmon core is not
hwmon code in AQR driver will not get compiled because of macro
IS_REACHABLE(CONFIG_HWMON) evaluating to false.
Signed-off-by: Robert Marko <robimarko@gmail.com>