drm/mediatek: dpi: Add kernel document for struct mtk_dpi_conf

This driver will support dp_intf and there are many configs between dpi
and dp_intf. Therefore, we will add many configs in "struct mtk_dpi_conf".
To let this structure more readable, we add this kernel doc.
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220701035845.16458-4-rex-bc.chen@mediatek.com/Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_dpi.c

@@ -118,6 +118,15 @@ struct mtk_dpi_yc_limit {
 	u16 c_bottom;
 };
 
+/**
+ * struct mtk_dpi_conf - Configuration of mediatek dpi.
+ * @cal_factor: Callback function to calculate factor value.
+ * @reg_h_fre_con: Register address of frequency control.
+ * @max_clock_khz: Max clock frequency supported for this SoCs in khz units.
+ * @edge_sel_en: Enable of edge selection.
+ * @output_fmts: Array of supported output formats.
+ * @num_output_fmts: Quantity of supported output formats.
+ */
 struct mtk_dpi_conf {
 	unsigned int (*cal_factor)(int clock);
 	u32 reg_h_fre_con;