drm/amdgpu/display: drop dcn301_calculate_wm_and_dl for now

drm/amdgpu/display: drop dcn301_calculate_wm_and_dl for now

[why]
 the dcn301_calculate_wm_and_dl() calculation exposed a issue
 - switch to dcn30 version for now.
 still need to follow up with dcn301 watermark updates version.

v2: squash in warning fix

Signed-off-by: Charles Sun <charles.sun@amd.com>
Reviewed-by: Nikola Cornij <nikola.cornij@amd.com>
Acked-by: Charles Sun <charles.sun@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>