storage: accept some UAS devices if streams are unavailable

On some older XHCIs streams are not supported and the UAS driver
will fail at probe time. For those devices storage should try
to bind to UAS devices.
This patch adds a flag for stream support to HCDs and evaluates
it.

[Note: Sarah fixed a bug where the USB 2.0 root hub, not USB 3.0 root
hub would get marked as being able to support streams.]

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>