usb: xhci-pci: Set PROBE_PREFER_ASYNCHRONOUS

usb: xhci-pci: Set PROBE_PREFER_ASYNCHRONOUS

This driver often takes on the order of 10ms to start, but in some cases
takes more than 100ms. It shouldn't have many cross-device dependencies
to race with, nor racy access to shared state with other drivers, so
this should be a relatively low risk change.

This driver was pinpointed as part of a survey of top slowest initcalls
(i.e., are built in, and probing synchronously) on a lab of ChromeOS
systems.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20221028184507.v2.2.I5a309231785d3a4e37118a25e84f5caa0136a343@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>