Set flag correctly in the TIDA comparitor auto range setting

the "first" flag was set to ensure that the range was always set for the first time round the loop, but then this was set explicitly and the loop started from 1, so ths meant that the first values from the loop were always being overwritten by the second values from the loop, and then only compared with the later values.

This fixes that.

None of the code in this package is used in any of the CI tests, so as long as this code compiles, it be accepted immediately, even if the CI tests which run athena fail.