xhci: Don't defer primary roothub registration if there is only one roothub

xhci: Don't defer primary roothub registration if there is only one roothub

The support for xHCI controllers with only one roothub, and the code
to defer primary roothub registation until second roothub got merged
to usb-next for 5.19 at the same time.

commit 873f323618c2 ("xhci: prepare for operation w/o shared hcd")
commit b7a4f9b5d0e4 ("xhci: Set HCD flag to defer primary roothub
registration")

These got merged in such a way that the flag to defer primary roothub
registration is set even for xHC controllers with just one roothub.

Fix this by setting the defer flag in a codepath taken only if we have
two roothubs

Fixes: 873f323618c2 ("xhci: prepare for operation w/o shared hcd")
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220516094850.19788-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>