drm/amdgpu: Delete an unnecessary check before two function calls

[Markus Elfring]

> The functions “debugfs_remove” and “kfree” test whether their argument
> is NULL and then return immediately.
> Thus the tests around the shown calls are not needed.
>
> This issue was detected by using the Coccinelle software.

I suggest to take another look at a similar patch.

drm/amdgpu: remove the redundant null check
https://lkml.org/lkml/2019/9/3/59
https://lore.kernel.org/patchwork/patch/1123118/
https://lore.kernel.org/r/1567491305-18320-1-git-send-email-zhongjiang@huawei.com/

Regards,
Markus