drm/amdgpu: remove the redundant null checks

debugfs_remove and kfree has taken the null check in account.
hence it is unnecessary to check it. Just remove the condition.
No functional change.

This issue was detected by using the Coccinelle software.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c

@@ -1077,7 +1077,6 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 
 	ttm_bo_unlock_delayed_workqueue(&adev->mman.bdev, resched);
 
-	if (fences)
 	kfree(fences);
 
 	return 0;
@@ -1103,7 +1102,6 @@ int amdgpu_debugfs_init(struct amdgpu_device *adev)
 
 void amdgpu_debugfs_preempt_cleanup(struct amdgpu_device *adev)
 {
-	if (adev->debugfs_preempt)
 	debugfs_remove(adev->debugfs_preempt);
 }