frontend: enable localization of usb support types

Change the translations of UsbPolicy enum values to reside in
LocalizedEnums instead of Enums, in order to make it possible to
localize them.

Change-Id: Icc23c2d8597e7d270c0390eb136a0f123fe0e16f
Signed-off-by: Arik Hadas <ahadas@redhat.com>