Fix ATLAS_MAP_ENTRY_FIELD_COUNT

Bug: 22558805

Change a039182d reduced
the size of an entry from 4 fields to 3, but failed to
update the constant that determined the size of the java long[].

Because the long[] is blindly passed down through to native, this
will result in reading past the end of the array as the size
is no longer a multiple of the number of fields being read so
the loop will not terminate until 1 iteration past the end.

Change-Id: I2f8e26cec9a60b3a74739a3763203296be5f1fd6