crypto: ccp - Ensure psp_ret is always init'd in __sev_platform_init_locked()

Initialize psp_ret inside of __sev_platform_init_locked() because there
are many failure paths with PSP initialization that do not set
__sev_do_cmd_locked().

Fixes: e423b9d7: ("crypto: ccp - Move SEV_INIT retry for corrupted data")

Signed-off-by: Peter Gonda <pgonda@google.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: John Allen <john.allen@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>