KVM: x86: Move nVMX's consistency check macro to common code

Move KVM's CC() macro to x86.h so that it can be reused by nSVM.
Debugging VM-Enter is as painful on SVM as it is on VMX.

Rename the more visible macro to KVM_NESTED_VMENTER_CONSISTENCY_CHECK
to avoid any collisions with the uber-concise "CC".

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210204000117.3303214-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>