drm/amdgpu: remove partition attributes sys file for gfx_v9_4_3

For driver de-init like rmmod operations those partition specific
attributes need to be removed accordingly.

Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>
Reviewed-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>