qdev-monitor: Avoid device_add crashing on non-device driver name
Watch this:
$ upstream-qemu -nodefaults -S -display none -monitor stdio
QEMU 1.7.50 monitor - type 'help' for more information
(qemu) device_add rng-egd
/work/armbru/qemu/qdev-monitor.c:491:qdev_device_add: Object 0x2089b00 is not an instance of type device
Aborted (core dumped)
Crashes because "rng-egd" exists, but isn't a subtype of TYPE_DEVICE.
Broken in commit
18b6dad.
Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>