UrfDeviceKernel: fix type for urf_device_kernel_update_states first parameter.

Signed-off-by: Mathieu Trudel-Lapierre <mathieu.trudel-lapierre@canonical.com>
UrfDaemon: add signal for flight mode state changes.

Signed-off-by: Mathieu Trudel-Lapierre <mathieu.trudel-lapierre@canonical.com>
Adapt liburfkill-glib to generic devices