LU-9480 lnet: add "lnetctl ping" command

LU-9480 lnet: add "lnetctl ping" command

Adds function jt_ping() in lnetctl.c and
lustre_lnet_ping_nid() in liblnetconfig.c file.
The output of "lnetctl ping" is similar to
"lnetctl peer show".

Function jt_ping() in lnetctl.c calls lustre_lnet_ping_nid()
to implement "lnetctl ping". Adds a function infra_ping_nid()
to be later reused for the ping similar lnetctl commands.
Uses a new ioctl call, IOC_LIBCFS_PING_PEER for "lnetctl ping".
With "lnetctl ping", multiple nids can be pinged. Uses a new
struct(lnet_ioctl_ping_data in lib-dlc.h) to pass the data
from kernel to user space for ping. Also changes lnet_ping()
function and its input parameters in lnet/lnet/api-ni.c

Test-Parameters: trivial
Signed-off-by: Sonia Sharma <sonia.sharma@intel.com>
Signed-off-by: Olaf Weber <olaf@sgi.com>
Change-Id: I67024d87fa5cca6aa7ff7a8099d4400a795f3a83
Reviewed-on: https://review.whamcloud.com/25791
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Tested-by: Amir Shehata <amir.shehata@intel.com>