LU-8660 mgs: handle return code of server_make_name()

LU-8660 mgs: handle return code of server_make_name()

Make sure server_make_name() actually succeeded when
called in mkfs_lustre utility and mgs_set_index().

Change-Id: I218351f0f3dd98e1b928664f872c1702a419a7cc
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/22867
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>