dt-bindings: usb: xhci: Add support for BCM2711

The xHCI IP on the BCM2711 SoC is compatible to "brcm,xhci-brcm-v2",
but also requires a power domain. So introduce a new compatible
and the specific constraints. Since the key allOf can only occur
once, merge the reference below.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20231205200531.8232-2-wahrenst@gmx.net


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