dt-bindings: irqchip: renesas-irqc: Document R-Car M3-W, V3M, D3 support

Document support for the Interrupt Controller for Externel Devices
(INTC-EX) in the Renesas M3-W (r8a7796), V3M (r8a77970), and D3
(r8a77995) SoCs.

No driver update is needed.
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

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

@@ -13,6 +13,9 @@ Required properties:
     - "renesas,irqc-r8a7793" (R-Car M2-N)
     - "renesas,irqc-r8a7794" (R-Car E2)
     - "renesas,intc-ex-r8a7795" (R-Car H3)
+    - "renesas,intc-ex-r8a7796" (R-Car M3-W)
+    - "renesas,intc-ex-r8a77970" (R-Car V3M)
+    - "renesas,intc-ex-r8a77995" (R-Car D3)
 - #interrupt-cells: has to be <2>: an interrupt index and flags, as defined in
   interrupts.txt in this directory
 - clocks: Must contain a reference to the functional clock.