drm/panel: ilitek-ili9881c: make use of prepare_prev_first

The panel.prepare() call requires an initialized MIPI-DSI host, so set
the prepare_prev_first flag to indicate that the host must be
initialized first.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231123-drm-panel-ili9881c-am8001280g-v1-1-fdf4d624c211@pengutronix.deSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231123-drm-panel-ili9881c-am8001280g-v1-1-fdf4d624c211@pengutronix.de

drivers/gpu/drm/panel/panel-ilitek-ili9881c.c

@@ -1094,6 +1094,8 @@ static int ili9881c_dsi_probe(struct mipi_dsi_device *dsi)
 		return ret;
 	}
 
+	ctx->panel.prepare_prev_first = true;
+
 	ret = drm_panel_of_backlight(&ctx->panel);
 	if (ret)
 		return ret;