ARM: dts: meson-sm1: add U-Boot specific DT for graphics

Rename meson-g12a-u-boot.dtsi into meson-g12-common-u-boot.dtsi to
match the new DT architecture and add meson-sm1-sei610-u-boot.dtsi
to handle the U-Boot specific DT for graphics.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/arch/arm/dts/meson-g12a-sei510-u-boot.dtsi b/arch/arm/dts/meson-g12a-sei510-u-boot.dtsi
index fddffd6..236f246 100644
--- a/arch/arm/dts/meson-g12a-sei510-u-boot.dtsi
+++ b/arch/arm/dts/meson-g12a-sei510-u-boot.dtsi
@@ -4,4 +4,4 @@
  * Author: Neil Armstrong <narmstrong@baylibre.com>
  */
 
-#include "meson-g12a-u-boot.dtsi"
+#include "meson-g12-common-u-boot.dtsi"