usb/gadget: Fix "high bandwidth" check in usb_gadget_ep_match_desc()

The current code tries to test for bits that are masked out by
usb_endpoint_maxp(). Instead, use the proper accessor to access
the new high bandwidth bits.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>