smb: server: stop sending fake security descriptors

smb: server: stop sending fake security descriptors

in smb2_get_info_sec, a dummy security descriptor (SD) is returned if
the requested information is not supported.

the code is currently wrong, as DACL_PROTECTED is set in the type field,
but there is no DACL is present.

instead of faking a security, report a STATUS_NOT_SUPPORTED error.

this seems to fix a "Error 0x80090006: Invalid Signature" on file
transfers with Windows 11 clients (25H2, build 26200.8246).

capturing traffic shows that the client is sending a GET_INFO/SEC_INFO
request, with the additional_info field set to 0x20
(ATTRIBUTE_SECURITY_INFORMATION). Returning an empty SD
(with only SELF_RELATIVE set) does not fix the error.

Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>