dt-bindings: usb: dwc3: Add Frame Length Adj constraints

dt-bindings: usb: dwc3: Add Frame Length Adj constraints

In accordance with the IP core databook the
snps,quirk-frame-length-adjustment property can be set within [0, 0x3F].
Let's make sure the DT schema applies a correct constraints on the
property.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-15-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>