ide: Fix info qtree for ide-drive.ver

Show the actual default value instead of <null> when the property has
not been set.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/ide/qdev.c

@@ -110,6 +110,9 @@ static int ide_drive_initfn(IDEDevice *dev)
 
     ide_init_drive(s, dev->conf.dinfo, dev->version, serial);
 
+    if (!dev->version) {
+        dev->version = qemu_strdup(s->version);
+    }
     if (!dev->serial) {
         dev->serial = qemu_strdup(s->drive_serial_str);
     }