drm/amdgpu: Remove unused print__rq_dlg_params_st

print__rq_dlg_params_st() was added in 2017 by
commit 061bfa06 ("drm/amdgpu/display: Add dml support for DCN")
but has remained unused.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>