swtpm_setup: Create IAK hwSerialNum from data extracted from EK certificate

Create the IAK hwSerialNum from the authority key identifier (AKID) and
serial number extracted from the EK certificate.

Adjust a test script that now needs to use a valid certificate for the EK
so that we can get the AKID and serial from it to create the serial number
for the IAK certificate.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>