Platform/RaspberryPi: Break XHCI into its own SSDT

Lets prepare to switch between XHCI and PCI by moving
the XHCI definition into its own SSDT. That way we can
select it based on the menu settings. The resource
producer/consumer flag is also corrected.

Reviewed-by: Andrei Warkentin <awarkentin@vmware.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Tested-by: Jared McNeill <jmcneill@invisible.ca>