drm/amdgpu: enable GTT fallback handling for dGPUs only

That is just a waste of time on APUs.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3704
Fixes: 216c128 ("drm/amdgpu: use GTT only as fallback for VRAM|GTT")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e8fc090)
Cc: stable@vger.kernel.org

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

@@ -161,7 +161,8 @@ void amdgpu_bo_placement_from_domain(struct amdgpu_bo *abo, u32 domain)
 		 * When GTT is just an alternative to VRAM make sure that we
 		 * only use it as fallback and still try to fill up VRAM first.
 		 */
-		if (domain & abo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM)
+		if (domain & abo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM &&
+		    !(adev->flags & AMD_IS_APU))
 			places[c].flags |= TTM_PL_FLAG_FALLBACK;
 		c++;
 	}