Fixed the default value of telephony proto.

Added default value for the proto. Also fixed some off-by-1
issues.

Test: runtest -x frameworks/opt/telephony/tests/telephonytests/src/
com/android/internal/telephony/metrics/TelephonyMetricsTest.java

bug: 32622214
Change-Id: Ib58881c9f50c87f14e931e2c996789f3680277b8