cifs: lease key is uninitialized in smb1 paths

It is cleaner to set lease key to zero in the places where leases are not
supported (smb1 can not return lease keys so the field was uninitialized).

Addresses-Coverity: 1513994 ("Uninitialized scalar variable")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>