LU-930 utils: fix 'lfs find' error message

LU-930 utils: fix 'lfs find' error message

Print out the actual filename supplied to "lfs find" rather than the
last argument in the list.  Otherwise we get error messages like:

    $ lfs find /myth/tmp -name fasdfasf -size 12
    error: find failed for 12.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I56eef89ab3c04b193f1c7dec3852c4038b3ebbe5
Reviewed-on: https://review.whamcloud.com/35740
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>