This reverts "drm/ttm: Fix configuration error around populate_and_map()
functions".

This fix has gone into the wrong direction. Those helpers should be
available even when neither CONFIG_INTEL_IOMMU nor CONFIG_SWIOTLB are
set.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NMichel Dänzer <michel.daenzer@amd.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>