qemu: Adjust ATTRIBUTE_NONNULL

Commit 7bf679ae removed the @json argument from the qemuMonitorOpen
prototype; however, it did not update the ATTRIBUTE_NONNULL value
which causes a build failure for when checking is enabled such as
when lv_cv_static_analysis is enabled.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_monitor.h

@@ -343,7 +343,7 @@ qemuMonitorPtr qemuMonitorOpen(virDomainObjPtr vm,
                                unsigned long long timeout,
                                qemuMonitorCallbacksPtr cb,
                                void *opaque)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(6);
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(5);
 qemuMonitorPtr qemuMonitorOpenFD(virDomainObjPtr vm,
                                  int sockfd,
                                  qemuMonitorCallbacksPtr cb,