NTB: ntb_test: Update ntb_tool MW tests

There are devices (like IDT PCIe switches), which outbound MWs xlat address
is setup on peer side. In this case local side is supposed to allocate
a memory buffer and somehow deliver the xlat DMA address to peer so one
could set the outbound MW up. The MW test is altered so to support both
previous Intel/AMD and new IDT-like devices.

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