staging: erofs: support statx

statx() has already been supported in commit a528d35e
("statx: Add a system call to make enhanced file info available"),
user programs can get more useful attributes.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>