bug: DFS namespaces with non-ASCII symbols cannot be mounted

[Eugene Korenevsky <ekorenevsky@xxxxxxxxxxxxx>]

Please pay attention to the bug:
https://bugzilla.kernel.org/show_bug.cgi?id=215440

The patch in previous message is a solution.

But the problem is more
global: after tis patch, Windows SMB server returns undocumented response
STATUS_OBJECT_NAME_INVALID to SMB2 CREATE request for DFS referrals at
non-ASCII DFS namespace. And 'ls' for mounted  non-ASCII DFS namespace
fails.