dm: dts: Convert driver model tags to use new schema

Now that Linux has accepted these tags, move the device tree files in
U-Boot over to use them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/serial.dtsi b/arch/x86/dts/serial.dtsi
index 22f7b54..99022eb 100644
--- a/arch/x86/dts/serial.dtsi
+++ b/arch/x86/dts/serial.dtsi
@@ -1,6 +1,6 @@
 / {
 	serial: serial {
-		u-boot,dm-pre-reloc;
+		bootph-all;
 		compatible = "ns16550";
 		reg = <0x3f8 8>;
 		reg-shift = <0>;