usb: wusbcore: combine multiple isoc frames in a single transfer request.

Combine multiple isoc frames in a single transfer request.  This allows
the HWA to take advantage of bursting to deliver data to endpoints
whose logical service interval is less than the minimum wireless USB
service interval of 4ms.  Wireless audio quality is much improved after
this update.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>