dt-bindings: clock: renesas: Remove R-Car Gen2 legacy DT bindings

As of commit 362b334b ("ARM: dts: r8a7791: Convert to new
CPG/MSSR bindings"), all upstream R-Car Gen2 device tree source files
use the unified "Renesas Clock Pulse Generator / Module Standby and
Software Reset" DT bindings.

Hence remove the old R-Car Gen2 DT bindings describing a hierarchical
representation of the various CPG and MSTP clocks.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20191016145207.29779-1-geert+renesas@glider.be

Documentation/devicetree/bindings/clock/renesas,rcar-gen2-cpg-clocks.txt

-* Renesas R-Car Gen2 Clock Pulse Generator (CPG)
-
-The CPG generates core clocks for the R-Car Gen2 SoCs. It includes three PLLs
-and several fixed ratio dividers.
-The CPG also provides a Clock Domain for SoC devices, in combination with the
-CPG Module Stop (MSTP) Clocks.
-
-Required Properties:
-
-  - compatible: Must be one of
-    - "renesas,r8a7790-cpg-clocks" for the r8a7790 CPG
-    - "renesas,r8a7791-cpg-clocks" for the r8a7791 CPG
-    - "renesas,r8a7792-cpg-clocks" for the r8a7792 CPG
-    - "renesas,r8a7793-cpg-clocks" for the r8a7793 CPG
-    - "renesas,r8a7794-cpg-clocks" for the r8a7794 CPG
-    and "renesas,rcar-gen2-cpg-clocks" as a fallback.
-
-  - reg: Base address and length of the memory resource used by the CPG
-
-  - clocks: References to the parent clocks: first to the EXTAL clock, second
-    to the USB_EXTAL clock
-  - #clock-cells: Must be 1
-  - clock-output-names: The names of the clocks. Supported clocks are "main",
-    "pll0", "pll1", "pll3", "lb", "qspi", "sdh", "sd0", "sd1", "z", "rcan", and
-    "adsp"
-  - #power-domain-cells: Must be 0
-
-SoC devices that are part of the CPG/MSTP Clock Domain and can be power-managed
-through an MSTP clock should refer to the CPG device node in their
-"power-domains" property, as documented by the generic PM domain bindings in
-Documentation/devicetree/bindings/power/power_domain.txt.
-
-
-Examples
---------
-
-  - CPG device node:
-
-	cpg_clocks: cpg_clocks@e6150000 {
-		compatible = "renesas,r8a7790-cpg-clocks",
-			     "renesas,rcar-gen2-cpg-clocks";
-		reg = <0 0xe6150000 0 0x1000>;
-		clocks = <&extal_clk &usb_extal_clk>;
-		#clock-cells = <1>;
-		clock-output-names = "main", "pll0, "pll1", "pll3",
-				     "lb", "qspi", "sdh", "sd0", "sd1", "z",
-				     "rcan", "adsp";
-		#power-domain-cells = <0>;
-	};
-
-
-  - CPG/MSTP Clock Domain member device node:
-
-	thermal@e61f0000 {
-		compatible = "renesas,thermal-r8a7790", "renesas,rcar-thermal";
-		reg = <0 0xe61f0000 0 0x14>, <0 0xe61f0100 0 0x38>;
-		interrupts = <0 69 IRQ_TYPE_LEVEL_HIGH>;
-		clocks = <&mstp5_clks R8A7790_CLK_THERMAL>;
-		power-domains = <&cpg_clocks>;
-	};