gfs2: glock holder GL_NOPID fix

Glocks are always actively acquired by processes, but as indicated by
the GL_NOPID holder flag, some of them are then associated with objects
like cached inodes rather than the process that acquired them.  As such,
for those glock holders, it makes little sense to dump which processes
originally acquired them.

Therefore, gfs2 is trying to hide the identity of the processes that
acquired those glocks.  The code for doing that is incorrect though, so
fix it.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>