irqchip: renesas-irqc: Add binding docs for new R-Car Gen2 SoCs

  - r8a7792 (R-Car V2H)
  - r8a7793 (R-Car M2-N)
  - r8a7794 (R-Car E2)

r8a7791 is now called "R-Car M2-W".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lkml.kernel.org/r/1409212800-4957-3-git-send-email-geert+renesas@glider.beSigned-off-by: Jason Cooper <jason@lakedaemon.net>

Documentation/devicetree/bindings/interrupt-controller/renesas,irqc.txt

@@ -6,7 +6,10 @@ Required properties:
   Examples with soctypes are:
     - "renesas,irqc-r8a73a4" (R-Mobile AP6)
     - "renesas,irqc-r8a7790" (R-Car H2)
-    - "renesas,irqc-r8a7791" (R-Car M2)
+    - "renesas,irqc-r8a7791" (R-Car M2-W)
+    - "renesas,irqc-r8a7792" (R-Car V2H)
+    - "renesas,irqc-r8a7793" (R-Car M2-N)
+    - "renesas,irqc-r8a7794" (R-Car E2)
 - #interrupt-cells: has to be <2>: an interrupt index and flags, as defined in
   interrupts.txt in this directory