drm/amd/pm: Disable MCLK switching with non-DC at 120 Hz+ (v2)

According to pp_pm_compute_clocks the non-DC display code
has "issues with mclk switching with refresh rates over 120 hz".
The workaround is to disable MCLK switching in this case.

Do the same for legacy DPM.

Fixes: 6ddbd37f ("drm/amd/pm: optimize the amdgpu_pm_compute_clocks() implementations")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>