rocker: Tweak stubbed out monitor commands' error messages

The QERR_ macros are leftovers from the days of "rich" error objects.
We've been trying to reduce their remaining use.

The stubbed out Rocker monitor commands are the last remaining users
of QERR_FEATURE_DISABLED.  They fail like this:

    (qemu) info rocker mumble
    Error: The feature 'rocker' is not enabled

The real rocker commands fail like this when the named object doesn't
exist:

    Error: rocker mumble not found

If that's good enough when Rocker is enabled, then it's good enough
when it's disabled, so replace QERR_FEATURE_DISABLED with that, and
drop the macro.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230207075115.1525-13-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>

hw/net/rocker/qmp-norocker.c

@@ -1,6 +1,5 @@
 /*
- * QMP Target options - Commands handled based on a target config
- *                      versus a host config
+ * QMP command stubs
  *
  * Copyright (c) 2015 David Ahern <dsahern@gmail.com>
  *
@@ -18,17 +17,16 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-rocker.h"
-#include "qapi/qmp/qerror.h"
 
 RockerSwitch *qmp_query_rocker(const char *name, Error **errp)
 {
-    error_setg(errp, QERR_FEATURE_DISABLED, "rocker");
+    error_setg(errp, "rocker %s not found", name);
     return NULL;
 };
 
 RockerPortList *qmp_query_rocker_ports(const char *name, Error **errp)
 {
-    error_setg(errp, QERR_FEATURE_DISABLED, "rocker");
+    error_setg(errp, "rocker %s not found", name);
     return NULL;
 };
 
@@ -37,7 +35,7 @@ RockerOfDpaFlowList *qmp_query_rocker_of_dpa_flows(const char *name,
                                                    uint32_t tbl_id,
                                                    Error **errp)
 {
-    error_setg(errp, QERR_FEATURE_DISABLED, "rocker");
+    error_setg(errp, "rocker %s not found", name);
     return NULL;
 };
 
@@ -46,6 +44,6 @@ RockerOfDpaGroupList *qmp_query_rocker_of_dpa_groups(const char *name,
                                                      uint8_t type,
                                                      Error **errp)
 {
-    error_setg(errp, QERR_FEATURE_DISABLED, "rocker");
+    error_setg(errp, "rocker %s not found", name);
     return NULL;
 };

include/qapi/qmp/qerror.h

@@ -29,9 +29,6 @@
 #define QERR_DEVICE_NO_HOTPLUG \
     "Device '%s' does not support hotplugging"
 
-#define QERR_FEATURE_DISABLED \
-    "The feature '%s' is not enabled"
-
 #define QERR_INVALID_PARAMETER \
     "Invalid parameter '%s'"