Commit 
4d89adc7b56f ("drm/i915/display/dsi: Add support to pipe D")
added pipe D support for DSI, but failed to update the state readout.
Fixes: 4d89adc7b56f ("drm/i915/display/dsi: Add support to pipe D")
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191211110844.2996-1-jani.nikula@intel.com
                case TRANS_DDI_EDP_INPUT_C_ONOFF:
                        trans_pipe = PIPE_C;
                        break;
+               case TRANS_DDI_EDP_INPUT_D_ONOFF:
+                       trans_pipe = PIPE_D;
+                       break;
                }
 
                if (trans_pipe == crtc->pipe) {