The lead user of this is the QDEV GPIO framework which will implement
GPIO disconnects via an "unlink". GPIO disconnection is used by
qtest's irq_intercept_out command.
Reviewed-by: Alexander Graf <agraf@suse.de> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>