CC3XX: Refactor the TRNG module

* Avoid using a global context in the TRNG module itself
* Refactor the call flow of TRNG need to follow, as now
  an explicit call to initialise the provided context has
  to be done

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I1db5641484d6f9fcafd57a3469768d748a708abd
7 files changed