dt-bindings: rng: starfive: Add jh8100 compatible string

Add compatible string for StarFive JH8100 trng.

Signed-off-by: Jia Jie Ho <jiajie.ho@starfivetech.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>