dt-bindings: usb: generic-ohci: Add HPE GXP ohci binding

Add hpe,gxp-ohci to the generic-ohci list. This is to
enable the device tree support.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
Link: https://lore.kernel.org/r/20220421192132.109954-10-nick.hawkins@hpe.com
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>