tpm: Use new ptm_cap_n structure for PTM_GET_CAPABILITY

tpm: Use new ptm_cap_n structure for PTM_GET_CAPABILITY

Use the new ptm_cap_n structure for getting the PTM_GET_CAPABILITY response
from swtpm. Previously only 17 bits could possibly have been set in ptm_cap
(uint64_t) in big endian order and those bits are now found in the 2nd
32bit word in the response in the caps field.

This data structure makes it now clear that the 1st 32bit word carries the
tpm_result like all the other response structures of all other commands
do.

The changes are taken from the swtpm project's tpm_ioctl.h.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>