dt-bindings: usb: xhci: Allow "iommus" and "dr_mode" properties

dt-bindings: usb: xhci: Allow "iommus" and "dr_mode" properties

Allow "iommus" property as it's reasonable for any XHCI controller to be
behind an IOMMU. Allow "dr_mode" as an XHCI controller can be part of a
dual-role controller.

In particular, the Marvell Armada 8K XHCI controller uses both of these
properties.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250919223433.2399927-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>