dt-bindings: usb: Convert generic USB properties to DT schemas

dt-bindings: usb: Convert generic USB properties to DT schemas

The generic USB properties have been described in the legacy bindings
text file: Documentation/devicetree/bindings/usb/generic.txt . Let's
convert its content into the generic USB, USB HCD and USB DRD DT
schemas. So the Generic USB schema will be applicable to all USB
controllers, USB HCD - for the generic USB Host controllers and the USB
DRD - for the USB Dual-role controllers.

Note the USB DRD schema is supposed to work in conjunction with
the USB peripheral/gadget and USB host controllers DT schemas.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-3-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>