drm/amdgpu: Do not evict VRAM on APUs with disabled HIBERNATE

Improve commit d796d844 (drm/radeon/kms: make hibernate work on IGPs) to
only migrate VRAM objects if the Linux kernel is actually built with
support for hibernation (suspend to disk).

The better solution is to get the information, if this is suspend or
hibernate, from `amdgpu_device_suspend()`, but that’s more involved, so
apply the simple solution first.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=107277
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1019,10 +1019,12 @@ int amdgpu_bo_unpin(struct amdgpu_bo *bo)
 int amdgpu_bo_evict_vram(struct amdgpu_device *adev)
 {
 	/* late 2.6.33 fix IGP hibernate - we need pm ops to do this correct */
-	if (0 && (adev->flags & AMD_IS_APU)) {
+#ifndef CONFIG_HIBERNATION
+	if (adev->flags & AMD_IS_APU) {
 		/* Useless to evict on IGP chips */
 		return 0;
 	}
+#endif
 	return ttm_bo_evict_mm(&adev->mman.bdev, TTM_PL_VRAM);
 }