tpm: vtpm_proxy: Prevent userspace from sending driver command

To prevent userspace from sending the TPM driver command to set
the locality, we need to check every command that is sent from
user space. To distinguish user space commands from internally
sent commands we introduce an additional state flag
STATE_DRIVER_COMMAND that is set while the driver sends this
command. Similar to the TPM 2 space commands we return an error
code when this command is detected.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>