Adjust wide_counter_csr_t::written_value() to only increment if counting is enabled, Bug Fix for PR 1381

[rbuchner-aril]

There looks to be a bug in the wide_counter_csr_t::written_value() when is_counting_enabled() == false. This bug was introduced in PR 1381, specifically in c927773.

The control flow for this is:

void csr_t::write(const reg_t val) noexcept {
  const bool success = unlogged_write(val);
  if (success) {
    log_write();
  }
}

First calls unlogged_write()

bool wide_counter_csr_t::unlogged_write(const reg_t val) noexcept {
  this->val = val;
  // The ISA mandates that if an instruction writes instret, the write
  // takes precedence over the increment to instret.  However, Spike
  // unconditionally increments instret after executing an instruction.
  // Correct for this artifact by decrementing instret here.
  // Ensure that Smctrpmf hasn't disabled counting.
  if (is_counting_enabled()) {
    this->val--;
  }
  return true;
}

If !is_counting_enabled(), then this->val is not decremented.

However, log_write() calls written_value()

void csr_t::log_write() const noexcept {
  log_special_write(address, written_value());
}

reg_t wide_counter_csr_t::written_value() const noexcept {
  // Re-adjust for upcoming bump()
  return val + 1;
}

Which reports back an adjust version of val regardless.

@atulkharerivos could you please review this change