dt-bindings: rng: add BCM2711 RNG compatible

The BCM2711 has a RNG200 block, so document its compatible string.
Signed-off-by: NStefan Wahren <wahrenst@gmx.net>
Signed-off-by: NStephen Brennan <stephen@brennan.io>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/rng/brcm,iproc-rng200.txt

@@ -2,6 +2,7 @@ HWRNG support for the iproc-rng200 driver
 
 Required properties:
 - compatible : Must be one of:
+	       "brcm,bcm2711-rng200"
 	       "brcm,bcm7211-rng200"
 	       "brcm,bcm7278-rng200"
 	       "brcm,iproc-rng200"