KVM: nSVM: Add missing checks for reserved bits to svm_set_nested_state()

The path for SVM_SET_NESTED_STATE needs to have the same checks for the CPU
registers, as we have in the VMRUN path for a nested guest. This patch adds
those missing checks to svm_set_nested_state().

Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <20201006190654.32305-3-krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>