hw/arm/virt: vTPM support

hw/arm/virt: vTPM support

Let the TPM TIS SYSBUS device be dynamically instantiable
in ARM virt.  A device tree node is dynamically created
(TPM via MMIO).

The TPM Physical Presence interface (PPI) is not supported.

To run with the swtmp TPM emulator, the qemu command line must
be augmented with:

        -chardev socket,id=chrtpm,path=swtpm-sock \
        -tpmdev emulator,id=tpm0,chardev=chrtpm \
        -device tpm-tis-device,tpmdev=tpm0 \

swtpm/libtpms command line example:

swtpm socket --tpm2 -t -d --tpmstate dir=/tmp/tpm \
--ctrl type=unixio,path=swtpm-sock

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Message-id: 20200305165149.618-7-eric.auger@redhat.com
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>