Use logic in Z_SAFE_HOMING

Use logic in Z_SAFE_HOMING

From
```
if (home_all_axis || homeZ) {
  if (home_all_axis) {
  ...
  home z
  }
  else if (homeZ) { // Don't need to Home Z twice
  home z
  }
}

```
to
```
if (home_all_axis || homeZ) {
  if (home_all_axis) {
  ...
  }
  home z
}
```