LU-9667 lnet: Userspace control to show lnet peer stats

LU-9667 lnet: Userspace control to show lnet peer stats

Adding lustre_lnet_stats_peer() function to show
lnet peer's statistics.

Adding helper functions in liblnetconfig.c to traverse
the lnet peers sysfs structure and show their statistics.

Change-Id: Ib82754caace444999be3940f37d229747cdb5313
Test-Parameters: trivial
Signed-off-by: Sonia Sharma <sharmaso@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/32723
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>