qerror: QERR_DEVICE_IN_USE is no longer used, drop

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/include/qapi/qmp/qerror.h b/include/qapi/qmp/qerror.h
index 8dd9fcb..0c2689c 100644
--- a/include/qapi/qmp/qerror.h
+++ b/include/qapi/qmp/qerror.h
@@ -23,9 +23,6 @@
 #define QERR_DEVICE_HAS_NO_MEDIUM \
     "Device '%s' has no medium"
 
-#define QERR_DEVICE_IN_USE \
-    "Device '%s' is in use"
-
 #define QERR_DEVICE_NO_HOTPLUG \
     "Device '%s' does not support hotplugging"