don't mention disk controllers in generic controller errors

The controller element supports non-disk controller types too.

https://bugzilla.redhat.com/show_bug.cgi?id=960958
(cherry picked from commit c075f89f)

src/conf/domain_conf.c

@@ -12026,7 +12026,7 @@ virDomainDefCheckABIStability(virDomainDefPtr src,
 
     if (src->ncontrollers != dst->ncontrollers) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("Target domain disk controller count %zu "
+                       _("Target domain controller count %zu "
                          "does not match source %zu"),
                        dst->ncontrollers, src->ncontrollers);
         return false;

src/qemu/qemu_driver.c

@@ -5861,7 +5861,7 @@ qemuDomainAttachDeviceControllerLive(virQEMUDriverPtr driver,
         break;
     default:
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("disk controller bus '%s' cannot be hotplugged."),
+                       _("'%s' controller cannot be hotplugged."),
                        virDomainControllerTypeToString(cont->type));
         break;
     }
@@ -5976,7 +5976,7 @@ qemuDomainDetachDeviceControllerLive(virQEMUDriverPtr driver,
         break;
     default :
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("disk controller bus '%s' cannot be hotunplugged."),
+                       _("'%s' controller cannot be hotunplugged."),
                        virDomainControllerTypeToString(cont->type));
     }
     return ret;

src/qemu/qemu_hotplug.c

@@ -2301,7 +2301,7 @@ int qemuDomainDetachPciControllerDevice(virQEMUDriverPtr driver,
                                        dev->data.controller->type,
                                        dev->data.controller->idx)) < 0) {
         virReportError(VIR_ERR_OPERATION_FAILED,
-                       _("disk controller %s:%d not found"),
+                       _("controller %s:%d not found"),
                        virDomainControllerTypeToString(dev->data.controller->type),
                        dev->data.controller->idx);
         goto cleanup;