drm/amdgpu: remove unnecessary asic type check

The number of crtc should be 0 for ASICs that don't
have display engine. Remove the unnecessary asic type
check then.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>