drm/amdgpu: remove invalid resource->start check v2

The majority of those where removed in the commit aed01a68
("drm/amdgpu: Remove TTM resource->start visible VRAM condition v2")

But this one was missed because it's working on the resource and not the
BO. Since we also no longer use a fake start address for visible BOs
this will now trigger invalid mapping errors.

v2: also remove the unused variable
Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: aed01a68 ("drm/amdgpu: Remove TTM resource->start visible VRAM condition v2")
CC: stable@vger.kernel.org
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -557,7 +557,6 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_device *bdev,
 				     struct ttm_resource *mem)
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
-	size_t bus_size = (size_t)mem->size;
 
 	switch (mem->mem_type) {
 	case TTM_PL_SYSTEM:
@@ -568,9 +567,6 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_device *bdev,
 		break;
 	case TTM_PL_VRAM:
 		mem->bus.offset = mem->start << PAGE_SHIFT;
-		/* check if it's visible */
-		if ((mem->bus.offset + bus_size) > adev->gmc.visible_vram_size)
-			return -EINVAL;
 
 		if (adev->mman.aper_base_kaddr &&
 		    mem->placement & TTM_PL_FLAG_CONTIGUOUS)