dt-bindings: crypto: qcom,prng: Document SM8750 RNG

Document SM8750 compatible for the True Random Number Generator.

Signed-off-by: Gaurav Kashyap <quic_gaurkash@quicinc.com>
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>