Current xhci debug message doesn't always output bus number, so it's
hard to figure out it's from USB2 or USB3 root hub.

In addition to that, some port numbers are offset to 0 and others are
offset to 1. Use the latter to match the USB core.

So use "bus number - port index + 1" to make debug message consistent.
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200723144530.9992-2-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>