drm/amd/display: Convert to kdoc formats in dc/core/dc.c

Fixes the following gcc with W=1:

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:3483: warning: Cannot understand  * *******************************************************************************
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:4204: warning: Cannot understand  * *******************************************************************************

Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>