ARM: dts: r8a7794: Convert to new CPG/MSSR bindings

Convert the R-Car E2 SoC from the old "Renesas R-Car Gen2 Clock Pulse
Generator (CPG)", "Renesas CPG DIV6 Clock", and "Renesas CPG Module Stop
(MSTP) Clocks" DT bindings to the new unified "Renesas Clock Pulse
Generator / Module Standby and Software Reset" DT bindings.

This simplifies the DTS files, and allows to add support for reset
control later.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7794-alt.dts

@@ -167,8 +167,7 @@
 	pinctrl-names = "default";
 	status = "okay";
 
-	clocks = <&mstp7_clks R8A7794_CLK_DU0>,
-		 <&mstp7_clks R8A7794_CLK_DU1>,
+	clocks = <&cpg CPG_MOD 724>, <&cpg CPG_MOD 723>,
 		 <&x13_clk>, <&x2_clk>;
 	clock-names = "du.0", "du.1", "dclkin.0", "dclkin.1";