erofs: remove unnecessary enum entries

Opt_nouser_xattr and Opt_noacl are useless, so just remove them.

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20201005071550.66193-1-cgxu519@mykernel.net


Signed-off-by: Gao Xiang <hsiangkao@redhat.com>