LU-10182 utils: change MDT name too long error

LU-10182 utils: change MDT name too long error

Change the error message to something more generic.
fsname-MDT00 failed with "Name too long", which was wrong

Test-parameters: trivial

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: If7c7de080c75dfdc853ff6d06e98a8ed074279cb
Reviewed-on: https://review.whamcloud.com/29884
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Steve Guminski <stephenx.guminski@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>