KVM: nSVM: fix a typo in svm_leave_nested

When forcibly leaving the nested mode, we should switch to vmcb01

Fixes: 4995a368 ("KVM: SVM: Use a separate vmcb for the nested L2 guest")

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210503125446.1353307-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>