crypto: ccp - shutdown SEV firmware on kexec

The commit 97f9ac3d ("crypto: ccp - Add support for SEV-ES to the
PSP driver") added support to allocate Trusted Memory Region (TMR)
used during the SEV-ES firmware initialization. The TMR gets locked
during the firmware initialization and unlocked during the shutdown.
While the TMR is locked, access to it is disallowed.

Currently, the CCP driver does not shutdown the firmware during the
kexec reboot, leaving the TMR memory locked.

Register a callback to shutdown the SEV firmware on the kexec boot.

Fixes: 97f9ac3d

 ("crypto: ccp - Add support for SEV-ES to the PSP driver")
Reported-by: Lucas Nussbaum <lucas.nussbaum@inria.fr>
Tested-by: Lucas Nussbaum <lucas.nussbaum@inria.fr>
Cc: <stable@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>