dt-bindings: can: rcar_canfd: document r8a774b1 support

Document the support for rcar_canfd on R8A774B1 SoC devices.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1570717560-7431-3-git-send-email-fabrizio.castro@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

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

@@ -5,6 +5,7 @@ Required properties:
 - compatible: Must contain one or more of the following:
   - "renesas,rcar-gen3-canfd" for R-Car Gen3 and RZ/G2 compatible controllers.
   - "renesas,r8a774a1-canfd" for R8A774A1 (RZ/G2M) compatible controller.
+  - "renesas,r8a774b1-canfd" for R8A774B1 (RZ/G2N) compatible controller.
   - "renesas,r8a774c0-canfd" for R8A774C0 (RZ/G2E) compatible controller.
   - "renesas,r8a7795-canfd" for R8A7795 (R-Car H3) compatible controller.
   - "renesas,r8a7796-canfd" for R8A7796 (R-Car M3-W) compatible controller.
@@ -31,8 +32,8 @@ The name of the child nodes are "channel0" and "channel1" respectively. Each
 child node supports the "status" property only, which is used to
 enable/disable the respective channel.
 
-Required properties for R8A774A1, R8A774C0, R8A7795, R8A7796, R8A77965,
-R8A77990, and R8A77995:
+Required properties for R8A774A1, R8A774B1, R8A774C0, R8A7795, R8A7796,
+R8A77965, R8A77990, and R8A77995:
 In the denoted SoCs, canfd clock is a div6 clock and can be used by both CAN
 and CAN FD controller at the same time. It needs to be scaled to maximum
 frequency if any of these controllers use it. This is done using the below