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/arm/dts/k3-am64-ddr.dtsi b/arch/arm/dts/k3-am64-ddr.dtsi
index d651093..bd95a78 100644
--- a/arch/arm/dts/k3-am64-ddr.dtsi
+++ b/arch/arm/dts/k3-am64-ddr.dtsi
@@ -17,7 +17,7 @@
 		ti,ddr-freq2 = <DDRSS_PLL_FREQUENCY_2>;
 		ti,ddr-fhs-cnt = <DDRSS_PLL_FHS_CNT>;
 
-		u-boot,dm-spl;
+		bootph-pre-ram;
 
 		ti,ctl-data = <
 			DDRSS_CTL_0_DATA