drm/amd/display: Stop amdgpu_dm initialize when link nums greater than max_links

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Stop amdgpu_dm initialize when link nums greater than max_links [Why] Coverity report OVERRUN warning. There are only max_links elements within dc->links. link count could up to AMDGPU_DM_MAX_DISPLAY_INDEX 31. [How] Make sure link count less than max_links.