Fix for buffer overrun crash at copying nmea string

Add zero clearing of allocated nmea buffer to ensure
the nmea string is null terminated.

CRs-Fixed: 2041933
Fixes: 37987256
Fixes: 37911727
Test: Builds, GPS works, with NMEA on, inside/outside, w/o crash.

Change-Id: I7b9a52eee8baf2d0a269fc5e2ec95f12d1d7aece
2 files changed