DT: net: can: rcar_canfd: document R8A77970 bindings

Document the R-Car V3M (R8A77970) SoC support in the R-Car CAN-FD bindings.
Signed-off-by: NSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: NRamesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
Reviewed-by: NSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/rcar_canfd.txt

@@ -6,6 +6,7 @@ Required properties:
   - "renesas,rcar-gen3-canfd" for R-Car Gen3 compatible controller.
   - "renesas,r8a7795-canfd" for R8A7795 (R-Car H3) compatible controller.
   - "renesas,r8a7796-canfd" for R8A7796 (R-Car M3-W) compatible controller.
+  - "renesas,r8a77970-canfd" for R8A77970 (R-Car V3M) compatible controller.
 
   When compatible with the generic version, nodes must list the
   SoC-specific version corresponding to the platform first, followed by the