drm/amdgpu: use div64_ul for 32-bit compatibility v1

v1: replace casting to unsigned long with div64_ul

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Slava Abramov <slava.abramov@amd.com>
Tested-by: Slava Abramov <slava.abramov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed