dm: core: parse chosen node

This is the node that would contain, for example, the framebuffer setup
by an earlier stage.

Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index e67d428..3f9e788 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -478,6 +478,13 @@
 	wdt0: wdt@0 {
 		compatible = "sandbox,wdt";
 	};
+
+	chosen {
+		chosen-test {
+			compatible = "denx,u-boot-fdt-test";
+			reg = <9 1>;
+		};
+	};
 };
 
 #include "sandbox_pmic.dtsi"