tpm: add stubs

Commit c37cacabf2 moved tpm_cleanup() in the main loop exit, however this
function is not available when compiling with --disable-tpm.

Provides necessary stubs to keep code clean of #ifdef'fery.

Reported-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <20171023102903.256AF7456A0@zero.eik.bme.hu>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

stubs/Makefile.objs

@@ -28,6 +28,7 @@ stub-obj-y += runstate-check.o
 stub-obj-y += set-fd-handler.o
 stub-obj-y += slirp.o
 stub-obj-y += sysbus.o
+stub-obj-y += tpm.o
 stub-obj-y += trace-control.o
 stub-obj-y += uuid.o
 stub-obj-y += vm-stop.o

stubs/tpm.c

@@ -0,0 +1,33 @@
+/*
+ * TPM stubs
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "sysemu/tpm.h"
+#include "qmp-commands.h"
+
+int tpm_init(void)
+{
+    return 0;
+}
+
+void tpm_cleanup(void)
+{
+}
+
+TPMInfoList *qmp_query_tpm(Error **errp)
+{
+    return NULL;
+}
+
+TpmTypeList *qmp_query_tpm_types(Error **errp)
+{
+    return NULL;
+}
+
+TpmModelList *qmp_query_tpm_models(Error **errp)
+{
+    return NULL;
+}