drm/amdgpu/atom: add support for new div32 opcodes (v3)

Better precision than the regular div opcode.

v2: drop 64 bit divide
v3: fix op handling.  This actually is a 64 bit divide.

Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>