NTB: MFV 5ae0beb6: Enable link for Intel root port mode in probe

We skip actually bringing up Rootport/Transparent configurations, so
most of this doesn't apply. Original Linux commit log:

Link training should be enabled in the driver probe for root port mode.
We should not have to wait for transport to be loaded for this to
happen. Otherwise the ntb device will not show up on the transparent
bridge side of the link.

Authored by: Dave Jiang
Obtained from: Linux (Dual BSD/GPL driver)
Sponsored by: EMC / Isilon Storage Division