The PSP (Platform Security Processor) provides support for key management
commands in Secure Encrypted Virtualization (SEV) mode, along with
software-based Trusted Execution Environment (TEE) to enable third-party
Trusted Applications.

Therefore, introduce psp-dev.c and psp-dev.h files, which can invoke
SEV (or TEE) initialization based on platform feature support.

TEE interface support will be introduced in a later patch.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Co-developed-by: NDevaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: NDevaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: NRijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: NGary R Hook <gary.hook@amd.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>