dt-bindings: rng: Document BCM7211 RNG compatible string

BCM7211 features a RNG200 block, document its compatible string.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Herbert 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,bcm7211-rng200"
 	       "brcm,bcm7278-rng200"
 	       "brcm,iproc-rng200"
 - reg : base address and size of control register block