KVM: VMX: Do not skip the instruction if handle_dr injects a fault

If kvm_get_dr or kvm_set_dr reports that it raised a fault, we must not
advance the instruction pointer. Otherwise the exception will hit the
wrong instruction.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>