usbtest: Fix BOS control test for USB 2.01 devices.

Commit c952a8ba "usb: usbtest: add a
test case to support bos for queue control" will cause USB 2.01 and USB
2.10 devices with a BOS descriptor to fail case 15 of the control test.

The Link PM errata (released in 2007, updated in 2011) says:

"The value of the bcdUSB field in the standard USB 2.0 Device Descriptor
is used to indicate that the device supports the request to read the BOS
Descriptor (i.e.  GetDescriptor(BOS)). Devices that support the BOS
descriptor must have a bcdUSB value of 0201H or larger."

The current code says that non-SuperSpeed devices *must* return -EPIPE,
as this comment shows:

                /* sign of this variable means:
                 *  -: tested code must return this (negative) error code
                 *  +: tested code may return this (negative too) error code
                 */
                int                     expected = 0;

This means the test will fail with USB 2.01 and USB 2.10 devices that
provide a BOS descriptor.  Change it to only require a stall response if
the USB device bcdUSB is less than 2.01.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Huang Rui <ray.huang@amd.com>