ocfs2: remove unused declaration in header file

ocfs2: remove unused declaration in header file

The definition of ocfs2_global_read_dquot() has been removed since commit
fb8dd8d78014 ("ocfs2: Fix quota locking").  Let's remove the empty
declartion

Link: https://lkml.kernel.org/r/20240906055742.105024-1-zhangzekun11@huawei.com
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>