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/glock.h b/fs/gfs2/glock.h
index 32572f7..f7cdaa8 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -141,7 +141,7 @@
 	struct pid *pid;
 
 	/* Look in glock's list of holders for one with current task as owner */
-	spin_lock(&gl->gl_spin);
+	spin_lock(&gl->gl_lockref.lock);
 	pid = task_pid(current);
 	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 		if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
@@ -151,7 +151,7 @@
 	}
 	gh = NULL;
 out:
-	spin_unlock(&gl->gl_spin);
+	spin_unlock(&gl->gl_lockref.lock);
 
 	return gh;
 }