smb: smbdirect: set SMBDIRECT_KEEPALIVE_NONE before disable_delayed_work(&sc->idle...

smb: smbdirect: set SMBDIRECT_KEEPALIVE_NONE before disable_delayed_work(&sc->idle.timer_work);

This avoids a potential confusing log message from
smbdirect_connection_idle_timer_work() if it's already running.

This is a very small race windows and not really needed, but it feels
better when reading the code.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>