tpm/ppi: Enable submission of optional command parameter for PPI 1.3

This patch enables a user to specify the additional optional command
parameter by writing it into the request file:

   # echo "23 16" > request
   # cat request
   23 16

For backwards compatibility:

If only 1 parameter is given then we assume this is the operation request
number.

   # echo "5" > request
   # cat request
   5

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: David Safford <david.safford@ge.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>