LU-1577 lnet: should export lnet_net2ni

LU-1577 lnet: should export lnet_net2ni

We don't want to export lnet_net2ni_locked because it requires
an extra parameter CPT number, which is internal to LNet and
confusing to user, also, no LND is using it/should use it, however,
LND does need lnet_net2ni() which is an inline function and it is
referring lnet_net2ni_locked(), which means it forces us to export
lnet_net2ni_locked.
The way to fix should be simple, we can just dis-inline lnet_net2ni()
and export itself instead of exporting lnet_net2ni_locked.

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I251d42d47770211ae6238ee56972fb9aacd63599
Reviewed-on: http://review.whamcloud.com/3207
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Doug Oucharek <doug@whamcloud.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>