When trying to disable formatting, formatter adds extra = in the middle of a const definition

**To Reproduce**
Format:

```
const x // dslx-fmt::off
= u32 :1
// dslx-fmt::on
;
```

**Expected behavior**
output = input

**Actual behavior**

```
// dslx-fmt::off
const x = = u32 :1
// dslx-fmt::on
;
```