thunderbolt: Fix XDomain rx_lanes_show and tx_lanes_show

If the Inter-Domain link is operating in asymmetric TB_LINK_WIDTH_ASYM_TX
mode, the rx_lanes_show should return 1 since there is only one receiver
and tx_lanes_show should return 3 since there are 3 transmitters.

Signed-off-by: Mohammad Rahimi <rahimi.mhmmd@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>