hwrng: meson - remove not needed call to platform_set_drvdata

drvdata isn't used, therefore remove this call.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>