xhci: Fix isoc TD encoding.

An isochronous TD is comprised of one isochronous TRB chained to zero or
more normal TRBs.  Only the isoc TRB has the TBC and TLBPC fields.  The
normal TRBs must set those fields to zeroes.  The code was setting the
TBC and TLBPC fields for both isoc and normal TRBs.  Fix this.

This should be backported to stable kernels as old as 3.0, that contain
the commit b61d378f

 " xhci 1.0: Set
transfer burst last packet count field."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org