drm/amd/display: Fix array-index-out-of-bounds in dml2/FCLKChangeSupport

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix array-index-out-of-bounds in dml2/FCLKChangeSupport [Why] Potential out of bounds access in dml2_calculate_rq_and_dlg_params() because the value of out_lowest_state_idx used as an index for FCLKChangeSupport array can be greater than 1. [How] Currently dml2 core specifies identical values for all FCLKChangeSupport elements. Always use index 0 in the condition to avoid out of bounds access.