LU-10151 lnet: report better config error with lnetctl

LU-10151 lnet: report better config error with lnetctl

Configuring net or route currently reports generic
message on error. Adding specific error message for
the missing parameters.

With importing config from yaml file, specific
error messages help in finding the exact error.

Change-Id: I7d9bdeb2280f4548897d9958aab7d451b981e8bd
Signed-off-by: Sonia Sharma <sonia.sharma@intel.com>
Test-Parameters: trivial
Reviewed-on: https://review.whamcloud.com/29820
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Doug Oucharek <dougso@me.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>