ntb_hw_switchtec: Skip unnecessary re-setup of shared memory window for crosslink case

In case of NTB crosslink topology, the setting of shared memory window in
the virtual partition doesn't reset on peer's reboot. So skip the
unnecessary re-setup of shared memory window for that case.

Signed-off-by: Wesley Sheng <wesley.sheng@microchip.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>