CC3XX: Refactor the RNG module

 * Remove the capability of buffering LFSR output
 * Simplify the interface towards the LFSR
 * Refactor the implementation to allow easier support for plugging
   an external TRNG seamlessly
 * Move the TRNG HW related module in a separate source

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I370297fbe3d5dd95a7a586c66b33b679217172e7
5 files changed