Fix minor bugs in HcalPacker.cc

These bugs prevented HCAL Trigger Towers from properly being converted
to RAW.
processTrig now returns the size correctly

Previously processTrig always returned 0 because the "size" variable was set to
0, then not actually used to hold the size of the vector, and finally
returned. Now size is properly set to the size of the vector.
Add braces to if and for statements in HcalPacker