LU-9667 lnet: Add LNet net sysfs structure

LU-9667 lnet: Add LNet net sysfs structure

Adding APIs to create ksets, kobjects
and the attribute files for net sysfs directory
structure.

Callback functions for the LNet NI attributes
are added to be used to display statistics.

Change-Id: Id777dd799ab95d96f84d9513b7fb470bc5502ab6
Test-Parameters: forbuildonly
Signed-off-by: Sonia Sharma <sharmaso@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/31744
Tested-by: Jenkins
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>