drm/amdgpu: remove set but not used variables 'vm, bo'

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

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c: In function 'update_gpuvm_pte':
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:840:20: warning:
 variable 'bo' set but not used [-Wunused-but-set-variable]

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:838:20: warning:
 variable 'vm' set but not used [-Wunused-but-set-variable]

They're never used since introduction in a46a2cd1 ("drm/amdgpu: Add GPUVM
memory management functions for KFD")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -719,13 +719,7 @@ static int update_gpuvm_pte(struct amdgpu_device *adev,
 		struct amdgpu_sync *sync)
 {
 	int ret;
-	struct amdgpu_vm *vm;
-	struct amdgpu_bo_va *bo_va;
-	struct amdgpu_bo *bo;
-
-	bo_va = entry->bo_va;
-	vm = bo_va->base.vm;
-	bo = bo_va->base.bo;
+	struct amdgpu_bo_va *bo_va = entry->bo_va;
 
 	/* Update the page tables  */
 	ret = amdgpu_vm_bo_update(adev, bo_va, false);