[openib-general] uverbs ibv_reg_mr return same lkey value

[Roland Dreier]

    Roland> I don't see how it's possible to get L_Key 0 for any
    Roland> memory region (since that L_Key is reserved by Mellanox
    Roland> HCA firmware)

By the way, this is just a coincidence with the current HW and driver.
With a different HCA, it may be possible to get L_Key 0 for a memory
region, although of course each memory region will still have a
different L_Key.

 - R.