gfs2: document ip in __gfs2_holder_init kernel-doc comment

Building with W=1 reports:
Warning: fs/gfs2/glock.c:1248 function parameter 'ip' not described
in '__gfs2_holder_init'

The ip parameter was added when __gfs2_holder_init started saving the
gfs2_glock_nq_init caller's return address to gh_ip. This makes it
easier to backtrack which holder took the lock. Document @ip to silence
this warning.

Fixes: b016d9a ("gfs2: Save ip from gfs2_glock_nq_init")
Signed-off-by: Sukrut Heroorkar <hsukrut3@gmail.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: SukrutHerookar

fs/gfs2/glock.c

@@ -1241,7 +1241,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
  * @state: the state we're requesting
  * @flags: the modifier flags
  * @gh: the holder structure
- *
+ * @ip: caller's return address for debugging
  */
 
 void __gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,