drm/amd/display: Fix up missing 'dc' & 'pipe_ctx' kdoc parameters in delay_cursor_until_vupdate()
Fixes the following gcc with W=1:
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_hw_sequencer.c:1904: warning: Function parameter or member 'dc' not described in 'delay_cursor_until_vupdate'
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_hw_sequencer.c:1904: warning: Function parameter or member 'pipe_ctx' not described in 'delay_cursor_until_vupdate'