docs/specs/tpm: Correct header path name

Commit 8dc6701 introduce the documentation but an
incorrect path name was used. Fix that.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Message-id: 20200612085444.8362-2-philmd@redhat.com
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

docs/specs/tpm.rst

@@ -199,8 +199,8 @@ to be used with the passthrough backend or the swtpm backend.
 
 QEMU files related to TPM backends:
  - ``backends/tpm.c``
+ - ``include/sysemu/tpm.h``
  - ``include/sysemu/tpm_backend.h``
- - ``include/sysemu/tpm_backend_int.h``
 
 The QEMU TPM passthrough device
 -------------------------------