smb: client: use ParentLeaseKey in open_cached_dir

Implement ParentLeaseKey logic in open_cached_dir() by looking up the
parent cfid, copying its lease key into the fid struct, and setting
the appropriate lease flag.

Fixes: f047390a ("CIFS: Add create lease v2 context for SMB3")
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>