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>
diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c
index 241a399..fb2b42c 100644
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -50,7 +50,7 @@
 	struct gfs2_glock *gl = foo;
 
 	INIT_HLIST_BL_NODE(&gl->gl_list);
-	spin_lock_init(&gl->gl_spin);
+	spin_lock_init(&gl->gl_lockref.lock);
 	INIT_LIST_HEAD(&gl->gl_holders);
 	INIT_LIST_HEAD(&gl->gl_lru);
 	INIT_LIST_HEAD(&gl->gl_ail_list);