cifsd: set epoch in smb2_lease_break response

When running generic/591 after smb2 leases is enable, all smb2 lease ack
requests failed in ksmbd. because cifs client seems to support only smb2
v2 lease. So cifs doesn't update lease state in ack request if epoch is
not set in smb2 lease break request from ksmbd. epoch is used for smb2
v2 leases. So this patch add smb2 create v2 lease context and set
increased epoch in smb2 lease break response.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>