ksmbd: clean up lease response flags and directory leases

ksmbd: clean up lease response flags and directory leases

Do not echo reserved v1 lease flags back to clients. For lease v2
responses, only return BREAK_IN_PROGRESS and PARENT_LEASE_KEY_SET when
they are meaningful, and preserve the parent lease key in the response.

Allow directory leases whenever the request is a valid lease v2 request,
and initialize v2 lease epochs from the first server-granted state change.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>