main/cdr: Use 'time' when rescheduling batched CDRs as opposed to 'size'

When refactoring CDRs to use the configuration framework, a 'whoops' was
introduced where the CDR batch size was used when rescheduling a batch,
as opposed to the time duration. This patch corrects that obvious mistake.

ASTERISK-24426 #close
Reported by: Shane Blaser


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@425735 f38db490-d61c-443f-a65b-d21fe96a405b