Since statx, every filesystem should fill the attributes/attributes_mask
in routine getattr. But the generic_fillattr has not fill that, so add
ext2_getattr to do this. This can fix generic/424 while testing ext2.

Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>