xhci: Support extended burst isoc TRB structure used by xhci 1.1 for USB 3.1

The transfer burst count (TBC) field in the Isoc TRB does not fit the new
larger burst count available for USB 3.1 SSP Isoc tranfers.
xhci 1.1 solved this by reusing the TD size field for transfer burst count.
The Mult field was outgrown as well. xhci 1.1  controllers can calculate
Mult itself and is not set if the new layout is used.

xhci 1.1 controllers that support the new Isoc TRB format expose a
Extended TBC Capability (ETC). To take the new format into use the xhci
host controller driver needs to set a Extended TBC Enable (ETE) bit.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>