ARM: at91: Add ADC driver to at91sam9260/at91sam9g20 dtsi files

Now that the bulk of at91sam9g20-related nodes are located in at91sam9260.dtsi,
we have to re-create the path to this ADC node for SoC specific parts.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm/boot/dts/at91sam9g20.dtsi b/arch/arm/boot/dts/at91sam9g20.dtsi
index 0eb1a75..2a1d1ca 100644
--- a/arch/arm/boot/dts/at91sam9g20.dtsi
+++ b/arch/arm/boot/dts/at91sam9g20.dtsi
@@ -15,4 +15,12 @@
 	memory {
 		reg = <0x20000000 0x08000000>;
 	};
+
+	ahb {
+		apb {
+			adc0: adc@fffe0000 {
+				atmel,adc-startup-time = <40>;
+			};
+		};
+	};
 };