staging: erofs: correct all misused ENOTSUPP

As Chao pointed out [1], ENOTSUPP is used for NFS
protocol only, we should use EOPNOTSUPP instead...

[1] https://lore.kernel.org/lkml/108ee2f9-75dd-b8ab-8da7-b81c17bafbf6@huawei.com/



Reported-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190814103705.60698-3-gaoxiang25@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>