qdev: add return value to init() callbacks.

Sorry folks, but it has to be.  One more of these invasive qdev patches.

We have a serious design bug in the qdev interface:  device init
callbacks can't signal failure because the init() callback has no
return value.  This patch fixes it.

We have already one case in-tree where this is needed:
Try -device virtio-blk-pci (without drive= specified) and watch qemu
segfault.  This patch fixes it.

With usb+scsi being converted to qdev we'll get more devices where the
init callback can fail for various reasons.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/cs4231.c b/hw/cs4231.c
index 82e2f52..843f86e 100644
--- a/hw/cs4231.c
+++ b/hw/cs4231.c
@@ -167,7 +167,7 @@
     return 0;
 }
 
-static void cs4231_init1(SysBusDevice *dev)
+static int cs4231_init1(SysBusDevice *dev)
 {
     int io;
     CSState *s = FROM_SYSBUS(CSState, dev);
@@ -179,6 +179,7 @@
     register_savevm("cs4231", -1, 1, cs_save, cs_load, s);
     qemu_register_reset(cs_reset, s);
     cs_reset(s);
+    return 0;
 }
 
 static SysBusDeviceInfo cs4231_info = {