Add common platform_device and helper code to make the registration of
the built-in USB controllers easier on the board which are using them.
Also register the USB controller on the AP81 and PB44 boards.
Signed-off-by: NGabor Juhos <juhosg@openwrt.org>
Signed-off-by: NImre Kaloz <kaloz@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2442/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>