dm: video: sandbox: Convert sandbox to use driver model for video

Now that driver model support is available, convert sandbox over to use it.
We can remove a few of the special hooks that sandbox currently has.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
diff --git a/arch/sandbox/dts/sandbox.dts b/arch/sandbox/dts/sandbox.dts
index d2addb4..e3f02bf 100644
--- a/arch/sandbox/dts/sandbox.dts
+++ b/arch/sandbox/dts/sandbox.dts
@@ -117,6 +117,7 @@
 	};
 
 	lcd {
+		u-boot,dm-pre-reloc;
 		compatible = "sandbox,lcd-sdl";
 		xres = <1366>;
 		yres = <768>;