gfs2: Remove gl_spin define

Commit e66cf161 replaced the gl_spin spinlock in struct gfs2_glock with a
gl_lockref lockref and defined gl_spin as gl_lockref.lock (the spinlock in
gl_lockref).  Remove that define to make the references to gl_lockref.lock more
obvious.

Signed-off-by: Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/incore.h

@@ -334,9 +334,8 @@ struct gfs2_glock {
 	struct lm_lockname gl_name;
 
 	struct lockref gl_lockref;
-#define gl_spin gl_lockref.lock
 
-	/* State fields protected by gl_spin */
+	/* State fields protected by gl_lockref.lock */
 	unsigned int gl_state:2,	/* Current state */
 		     gl_target:2,	/* Target state */
 		     gl_demote_state:2,	/* State requested by remote node */