swtpm_setup: Get active PCR banks from swtpm_setup.conf

swtpm_setup: Get active PCR banks from swtpm_setup.conf

If the user did not provide the PCR banks to activate through the command
line options, try to read it from the config file and if nothing is found
there, fall back to the DEFAULT_PCR_BANKS as set during configure time.

Move the check for the PCR banks after the access check to the
configuration file.

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