ksmbd: set RSS capable in FSCTL_QUERY_NETWORK_INTERFACE_INFO

Set RSS capable in FSCTL_QUERY_NETWORK_INTERFACE_INFO if netdev has
multi tx queues. And add ksmbd_compare_user() to avoid racy condition
issue in ksmbd_free_user(). because windows client is simultaneously used
to send session setup requests for multichannel connection.

Tested-by: Ziwei Xie <zw.xie@high-flyer.cn>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>