trng: Move device memory retrieve to platform code

trng_adapter_init() was checking for device memory. However not every
trng implementation needs device memory. Instead we move the device
memory retrieval to the platform specific code.

Signed-off-by: Jelle Sels <jelle.sels@arm.com>
Change-Id: Ib4ebca98152900e471711a9106682cd43510057d
5 files changed