dt-bindings: usb: intel, keembay-dwc3: Validate DWC3 sub-node

Intel Keem Bay DWC3 compatible DT nodes are supposed to have a DWC USB3
compatible sub-node to describe a fully functioning USB interface. Let's
use the available DWC USB3 DT schema to validate the Intel Keem Bay DWC3
sub-nodes.

Note since the generic DWC USB3 DT node is supposed to be named as generic
USB HCD ("^usb(@.*)?") one we have to accordingly fix the sub-nodes name
regexp and fix the DT node example.

Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-20-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>