ARM: at91/dt: sam9260: correct external trigger value

The external trigger value is 0b1101 which is 13 but 0xd.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9260.dtsi

@@ -641,7 +641,7 @@
 				trigger@3 {
 					reg = <3>;
 					trigger-name = "external";
-					trigger-value = <0x13>;
+					trigger-value = <0xd>;
 					trigger-external;
 				};
 			};