USB: OHCI: fix logic for scheduling isochronous URBs

The isochronous scheduling logic in ohci-hcd has a bug.  The
calculation for skipping TDs that are too late should be carried out
only in the !URB_ISO_ASAP case.  When URB_ISO_ASAP is set, the URB is
pushed back so that none of the TDs are too late, which would cause
the calculation to overflow.

The patch also fixes the calculation to avoid overflow in the case
where the frame value wraps around.

This should be applied to -stable kernels going back to 3.8.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>