GFS2: Fix bug in gfs2_lock_fs_check_clean()

gfs2_lock_fs_check_clean() should not be calling gfs2_jindex_hold()
since it doesn't work like rindex hold, despite the comment. That
allows gfs2_jindex_hold() to be moved into ops_fstype.c where it
can be made static.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>