drm/amdgpu: remove set but not used variable 'invalid'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c: In function
‘amdgpu_amdkfd_evict_userptr’:
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1665:6: warning:
variable ‘invalid’ set but not used [-Wunused-but-set-variable]

'invalid' is never used, so can be removed. Thus 'atomic_inc_return'
can be replaced as 'atomic_inc'

Fixes: 5ae0283e ("drm/amdgpu: Add userptr support for KFD")
Signed-off-by: yu kuai <yukuai3@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1662,10 +1662,10 @@ int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem,
 				struct mm_struct *mm)
 {
 	struct amdkfd_process_info *process_info = mem->process_info;
-	int invalid, evicted_bos;
+	int evicted_bos;
 	int r = 0;
 
-	invalid = atomic_inc_return(&mem->invalid);
+	atomic_inc(&mem->invalid);
 	evicted_bos = atomic_inc_return(&process_info->evicted_bos);
 	if (evicted_bos == 1) {
 		/* First eviction, stop the queues */