ARM: dts: imx51-babbage: Add MC13892 ADC support

The MC13892 Analog-to-Digital input pins (ADIN5-7) are exposed on the
imx51-babbage board.

Pass the "fsl,mc13xxx-uses-adc" property so that the MC13892 ADC
block can work.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx51-babbage.dts

@@ -204,6 +204,7 @@ pmic: mc13892@0 {
 		reg = <0>;
 		interrupt-parent = <&gpio1>;
 		interrupts = <8 IRQ_TYPE_LEVEL_HIGH>;
+		fsl,mc13xxx-uses-adc;
 		fsl,mc13xxx-uses-rtc;
 
 		regulators {