uas: uas_alloc_data_urb: Remove unnecessary use_streams check

uas_alloc_data_urb always gets called with a stream_id value of 0 when not
using streams. Removing the check makes it consistent with uas_alloc_sense_urb.

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