Pull up following revision(s) (requested by skrll in ticket #459):
sys/dev/usb/xhci.c: 1.78, 1.83
PR/52791: Robert Sprowson: avoid duplicate tests (use accessor variables)
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Fix the logic around TT Hub Slot ID, TT Port Number and Multi-TT in
xhci_setup_tthub.  TT Hub/Port need to reference the upstream HS hub and
Multi-TT needs to reflect the capabilities of a HS hub itself or the same
upstream HS hub.

(snj)