When the writeback stage is present the retired instruction counter
(minstret) and the retired compressed instruction counter could see an
off by one error when an instruction was in the writeback stage when
reading the counters. With this fix the ID stage observes the
incremented value of the counters when an instruction that would
increment them is in writeback.
Fix a lint error reported by AscentLint:
```
E ALWAYS_SPEC: ibex_counter.sv:59 Edge triggered block may be more accurately modeled as always_ff New
```
