x86/kvm/Kconfig: Ensure CRYPTO_DEV_CCP_DD state at minimum matches KVM_AMD

Prevent a config where KVM_AMD=y and CRYPTO_DEV_CCP_DD=m thereby ensuring
that AMD Secure Processor device driver will be built-in when KVM_AMD is
also built-in.

v1->v2:
* Removed usage of 'imply' Kconfig option.
* Change patch commit message.

Fixes: 505c9e94 ("KVM: x86: prefer "depends on" to "select" for SEV")

Cc: <stable@vger.kernel.org> # 4.16.x
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/Kconfig

@@ -85,7 +85,7 @@ config KVM_AMD_SEV
 	def_bool y
 	bool "AMD Secure Encrypted Virtualization (SEV) support"
 	depends on KVM_AMD && X86_64
-	depends on CRYPTO_DEV_CCP && CRYPTO_DEV_CCP_DD && CRYPTO_DEV_SP_PSP
+	depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m)
 	---help---
 	Provides support for launching Encrypted VMs on AMD processors.