Move non-qdev-gpio[*] from /machine into /machine/unattached.
For the PC this moves 25 nodes from the stable namespace into the unstable.

Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Tested-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>