drm/amdgpu: Remove extra checks for CPX

As far as the number of XCCs, the number of compute partitions, and the
number of memory partitions qualify, CPX is valid.

Signed-off-by: Amber Lin <Amber.Lin@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>