usb-storage: Don't bind to uas devices if the uas driver is enabled

uas devices have 2 alternative settings on their usb-storage interface,
one for usb-storage and one for uas. Using the uas driver is preferred, so if
the uas driver is enabled, and the device has an uas alt setting, don't bind.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>