acpi: expose TPM/PPI configuration parameters to firmware via fw_cfg

acpi: expose TPM/PPI configuration parameters to firmware via fw_cfg

To avoid having to hard code the base address of the PPI virtual
memory device we introduce a fw_cfg file etc/tpm/config that holds the
base address of the PPI device, the version of the PPI interface and
the version of the attached TPM.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
[ Marc-André: renamed to etc/tpm/config, made it static, document it ]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>