The value of tmnxMobGtpPriGrpPrimaryCf specifies which compact flash
will be used as a primary storage for the Charging Data Records (CDR)
storage.
If the user tries to set the 'cf1' and if the 'cf1' is not available
then 'cf2' will be set as primary storage. If the user tries to set
the 'cf2' and if 'cf2' is not available then cf1 will be set as
primary storage.