This patch takes advantage of block transfer interrupts on Intel XHCI
controllers which is used during isochronous transfers. Because of a bug
in hardware (see usb_host_isoc_bei.patch header), this feature has been
disabled for Intel leading to up to 8000 interrupts/s for isochronous
transfer causing severe CPU consumption on Genode. With this commit we
lower host driver consumption to normal levels.
issue #4149
