crypto: caam - refactor RNG initialization

crypto: caam - refactor RNG initialization

RNG (re-)initialization will be needed on pm resume path,
thus refactor the corresponding code out of the probe callback.

Signed-off-by: Horia GeantA <horia.geanta@nxp.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@nxp.com>
Reviewed-by: Gaurav Jain <gaurav.jain@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>