ARM: dts: kirkwood: ts219: disable the SoC's RTC

The internal RTC doesn't work, loading the driver only yields

	rtc-mv f1010300.rtc: internal RTC not ticking

. So disable it.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Acked-by: Martin Michlmayr <tbm@cyrius.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>