arm64: dts: imx8mm-venice: Fix GSC vdd_bat data size.

On these boards, vdd_bat is 16bit, not 24bit.  Reading them as 24bit
values yield garbage values because of the additional byte, which is a
configurable fan trippoint[1].

So set their mode to mode_voltage_16bit = 3 instead of
mode_voltage_24bit = 1.

[1]: http://trac.gateworks.com/wiki/gsc#SystemTemperatureandVoltageMonitor

Only tested on GW7100.
Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Acked-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-venice-gw700x.dtsi

@@ -149,7 +149,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};

arch/arm64/boot/dts/freescale/imx8mm-venice-gw7901.dts

@@ -354,7 +354,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};

arch/arm64/boot/dts/freescale/imx8mm-venice-gw7902.dts

@@ -327,7 +327,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};

arch/arm64/boot/dts/freescale/imx8mm-venice-gw7903.dts

@@ -293,7 +293,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};

arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts

@@ -325,7 +325,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};

arch/arm64/boot/dts/freescale/imx8mp-venice-gw74xx.dts

@@ -281,7 +281,7 @@ channel@6 {
 			};
 
 			channel@8 {
-				gw,mode = <1>;
+				gw,mode = <3>;
 				reg = <0x08>;
 				label = "vdd_bat";
 			};