ARM: dts: imx28: Use correct compatible string for RTC

The "mxim" vendor prefix does not exit, though it looks like it might
have been a typo'ed "maxim". Still, no compatible string exists that
matches "maxim,ds1339". The closest is the "dallas,ds1339" and since
this node is named "rtc" that's probably the one that was intended.

Signed-off-by: Thierry Reding <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Acked-by: Lothar Waßmann <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx28-tx28.dts

···
 	};
 
 	ds1339: rtc@68 {
-		compatible = "mxim,ds1339";
+		compatible = "dallas,ds1339";
 		reg = <0x68>;
 		trickle-resistor-ohms = <250>;
 		trickle-diode-disable;