uas: fix GFP_NOIO under spinlock

Quote Dan:

The patch e36e6493: "uas: Use GFP_NOIO rather then GFP_ATOMIC
where possible" from Nov 7, 2013, leads to the following static
checker warning:

        drivers/usb/storage/uas.c:806 uas_eh_task_mgmt()
        error: scheduling with locks held: 'spin_lock:lock'

Some other allocations under spinlock are not caught.
The fix essentially reverts e36e6493

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>