staging: erofs: add error handling for xattr submodule

commit cadf1ccf1b0021d0b7a9347e102ac5258f9f98c8 upstream.

This patch enhances the missing error handling code for
xattr submodule, which improves the stability for the rare cases.

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