NTB: ntb_test: Update ntb_tool link tests

Link Up and Down methods are used to change NTB link settings on
local side only for multi-port devices. Link is considered up
only if both sides local and peer set it up. Intel/AMD hardware
acts a bit different by assigning the Primary and Secondary roles,
so Primary device only is able to change the link state. Such behaviour
should be reflected in the test code.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>