ARM: tegra: acer-a500: Correct compatible of ak8975 magnetometer

The "ak,ak8975" compatible is not recognized by dt-bindings, it's
deprecated. Use supported "asahi-kasei,ak8975" compatible.
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra20-acer-a500-picasso.dts

@@ -543,7 +543,7 @@ i2c@7000d000 {
 		status = "okay";
 
 		magnetometer@c {
-			compatible = "ak,ak8975";
+			compatible = "asahi-kasei,ak8975";
 			reg = <0x0c>;
 
 			interrupt-parent = <&gpio>;