gfs2: Fix __gfs2_holder_init function name in kernel-doc comment

The function name in the kernel-doc comment wasn't updated when the
function was renamed.

Fixes: b016d9a8 ("gfs2: Save ip from gfs2_glock_nq_init")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/glock.c

@@ -1245,7 +1245,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 }
 
 /**
- * gfs2_holder_init - initialize a struct gfs2_holder in the default way
+ * __gfs2_holder_init - initialize a struct gfs2_holder in the default way
  * @gl: the glock
  * @state: the state we're requesting
  * @flags: the modifier flags