drm/amd/display: change bw_dceip and bw_vbios into pointers

-Change bw_calcs_dceip into pointer
-Change bw_calcs_vbios into pointer

This is needed for flattening of core_dc into dc, as without this the
diags build fails

Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>