spapr: initial implementation for H_TPM_COMM/spapr-tpm-proxy

spapr: initial implementation for H_TPM_COMM/spapr-tpm-proxy

This implements the H_TPM_COMM hypercall, which is used by an
Ultravisor to pass TPM commands directly to the host's TPM device, or
a TPM Resource Manager associated with the device.

This also introduces a new virtual device, spapr-tpm-proxy, which
is used to configure the host TPM path to be used to service
requests sent by H_TPM_COMM hcalls, for example:

  -device spapr-tpm-proxy,id=tpmp0,host-path=/dev/tpmrm0

By default, no spapr-tpm-proxy will be created, and hcalls will return
H_FUNCTION.

The full specification for this hypercall can be found in
docs/specs/ppc-spapr-uv-hcalls.txt

Since SVM-related hcalls like H_TPM_COMM use a reserved range of
0xEF00-0xEF80, we introduce a separate hcall table here to handle
them.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com
Message-Id: <20190717205842.17827-3-mdroth@linux.vnet.ibm.com>
[dwg: Corrected #include for upstream change]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>