crypto: ccp: Use the stack and common buffer for status commands

[ Upstream commit 38103671 ]

Drop the dedicated status_cmd_buf and instead use a local variable for
PLATFORM_STATUS.  Now that the low level helper uses an internal buffer
for all commands, using the stack for the upper layers is safe even when
running with CONFIG_VMAP_STACK=y.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210406224952.4177376-7-seanjc@google.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stable-dep-of: 91dfd982 ("crypto: ccp - Avoid page allocation failure warning for SEV_GET_ID2")
Signed-off-by: Sasha Levin <sashal@kernel.org>