arm64: dts: renesas: Deduplicate extalr_clk bootph-all

Most R-Car Gen3 and Gen4 systems require extalr_clk very early
in the boot process. Currently the extalr_clk { bootph-all } DT
property to indicate this clock should be available early is set
in each SoC U-Boot DT extras file. Deduplicate this assignment to
new common r8a779x-rcar64-u-boot.dtsi file.

Note that R-Car Gen3 R8A77990 E3 and R8A77995 D3 and RZ R8A774C0
do not require extalr_clk early, therefore these SoCs still include
plain r8a779x-u-boot.dtsi in their U-Boot DT extras .

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/arch/arm/dts/r8a779g0-u-boot.dtsi b/arch/arm/dts/r8a779g0-u-boot.dtsi
index 2e731b6..10051c9 100644
--- a/arch/arm/dts/r8a779g0-u-boot.dtsi
+++ b/arch/arm/dts/r8a779g0-u-boot.dtsi
@@ -5,7 +5,7 @@
  * Copyright (C) 2021 Renesas Electronics Corp.
  */
 
-#include "r8a779x-u-boot.dtsi"
+#include "r8a779x-rcar64-u-boot.dtsi"
 
 / {
 	binman: binman {
@@ -139,10 +139,6 @@
 	bootph-all;
 };
 
-&extalr_clk {
-	bootph-all;
-};
-
 &hscif0 {
 	bootph-all;
 };