Drop qemu-objects.h from modules that don't require it

Previous commits dropped most qobjects usage from qemu modules
(now they are a low level interface used by the QAPI). However,
some modules still include the qemu-objects.h header file.

This commit drops qemu-objects.h from some of those modules
and includes qjson.h instead, which is what they actually need.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/vl.c b/vl.c
index 1ddb17b..fb28ffc 100644
--- a/vl.c
+++ b/vl.c
@@ -143,9 +143,9 @@
 #include "audio/audio.h"
 #include "migration.h"
 #include "kvm.h"
+#include "qjson.h"
 #include "qemu-option.h"
 #include "qemu-config.h"
-#include "qemu-objects.h"
 #include "qemu-options.h"
 #include "qmp-commands.h"
 #include "main-loop.h"