[moco-tf] Remove redundant codes in FuseBinaryIntoPreceding (#6319)

[moco-tf] Remove redundant codes in FuseBinaryIntoPreceding (#6319)

* [moco-tf] Remove redundant codes in FuseBinaryIntoPreceding

There are some redundant codes in `FuseBinaryIntoPreceding.cpp`
This commit will remove them.
- Exactly only one of variables(`xc` and `yc`) is `nullptr` because `is_only_one_valid` already checks.
- Then `addparam` and `mulparam` cannot be `nullptr`.
- After removing above condition, there can be only one case that `bchanged` can be returned, that is when `biasadd` is `nullptr`. However when `biasadd` is `nullptr`, bchanged is always `false`.

Signed-off-by: Seok NamKoong <sk.namkoong@samsung.com>
* apply comments

* add missing codes

* fix comments

* apply comments