tpm: add missing include

else file including "sysemu/tpm.h" fails to compile:

  In file included from qemu/stubs/tpm.c:2:0:
  qemu/include/sysemu/tpm.h:36:19: error: implicit declaration of function ‘object_resolve_path_type’ [-Werror=implicit-function-declaration]
       Object *obj = object_resolve_path_type("", TYPE_TPM_TIS, NULL);
                     ^~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

include/sysemu/tpm.h

@@ -13,6 +13,7 @@
 #define QEMU_TPM_H
 
 #include "qemu/option.h"
+#include "qom/object.h"
 
 typedef struct TPMState TPMState;