tpm: reorganize headers and split hardware part

The TPM subsystem does not have a full front-end/back-end separation.
The sole available backend, tpm_passthrough, depends on the data
structures of the sole available frontend, tpm_tis.

However, we can at least try to split the user interface (tpm.c) from the
implementation (hw/tpm).  The patches makes tpm.c not include tpm_int.h,
which is shared between tpm_tis.c and tpm_passthrough.c; instead it
moves more stuff to tpm_backend.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/tpm.h

@@ -0,0 +1,23 @@
+/*
+ * Public TPM functions
+ *
+ * Copyright (C) 2011-2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger    <stefanb@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#ifndef QEMU_TPM_H
+#define QEMU_TPM_H
+
+#include "qemu/option.h"
+
+typedef struct TPMState TPMState;
+
+int tpm_config_parse(QemuOptsList *opts_list, const char *optarg);
+int tpm_init(void);
+void tpm_cleanup(void);
+
+#endif /* QEMU_TPM_H */