fs/smb: Swing unicode common code from smb->NLS

Swing most of the inline functions and unicode tables into nls
from the copy in smb/server.  This is UCS-2 rather than most
of the rest of the code in NLS, but it currently seems like the
best place for it.

The actual unicode.c implementations vary much more between server
and client so they're unmoved.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>