PBAP: New Missed calls parameter not set correctly

When a PCE pull the missed-calls-phonebook (mch.vcf) from the PSE, a parameter
stating the number of _new_ missed calls must be included in the reply.
Currently the parameter is included but it is always set to zero, which is
incorrect.
This fix corrects the variable used for new missed calls

Bug: 13022843
Change-Id: I6094c50a76711cfff9347596d70ac2300cfbb543