Fix HCAL etaRange signature

Current HCAL TP code passes a signed `ieta` to towerEtaBounds, which passes this through to etaRange of the HcalTopology.  If `ieta` is negative, the sign of the result is reversed.  This currently fails for negative `ieta`, as etaRange will use the `ieta` as an array index.

Fix contains two parts:
* pass abs(`ieta`) instead of `ieta` to etaRange
* change the signature to indicate that positive values of `ieta` are desired
It compiles and runs fine, I think it must be implicitly converted in the function call by the compiler?  If I change ietaAbs to be of type unsigned int, the following comparison with `firstHFTower()` raises a sign-compare error.

Should fix this throughout?