dm: doc: Update device tree binding docs for new schema

Now that Linux has accepted these tags, move U-Boot over to use them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/device-tree-bindings/net/mdio-mux-reg.txt b/doc/device-tree-bindings/net/mdio-mux-reg.txt
index 0ac34dc..0f7c295 100644
--- a/doc/device-tree-bindings/net/mdio-mux-reg.txt
+++ b/doc/device-tree-bindings/net/mdio-mux-reg.txt
@@ -16,7 +16,7 @@
 
 &i2c0 {
 	status = "okay";
-	u-boot,dm-pre-reloc;
+	bootph-all;
 
 	fpga@66 {
 		#address-cells = <1>;