LU-16808 lfs: return invalid=-1 if no projid retrieved

LU-16808 lfs: return invalid=-1 if no projid retrieved

lfs find --printf "%LP" returns -1 as invalid projid if a
special file is found while it does not contain projid.

Fix bug where "lfs find --printf %LP" always printed "0".

Fixes: 6b8e97b76c ("LU-10378 utils: add formatted printf to lfs find")
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: Ic1b474145212e0ce091f97281440816d9a437a4f
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50916
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Thomas Bertschinger <bertschinger@lanl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>