drm/panel: xinpeng-xpp055c272: Stop tracking prepared

As talked about in commit d2aacaf07395 ("drm/panel: Check for already
prepared/enabled in drm_panel"), we want to remove needless code from
panel drivers that was storing and double-checking the
prepared/enabled state. Even if someone was relying on the
double-check before, that double-check is now in the core and not
needed in individual drivers.

Acked-by: Linus Walleij <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Reviewed-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Douglas Anderson <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.30.I2145be78ce28327f4588c2c21370f22fd79d28b8@changeid

drivers/gpu/drm/panel/panel-xinpeng-xpp055c272.c

···
 	struct gpio_desc *reset_gpio;
 	struct regulator *vci;
 	struct regulator *iovcc;
-	bool prepared;
 };
 
 static inline struct xpp055c272 *panel_to_xpp055c272(struct drm_panel *panel)
···
 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
 	int ret;
 
-	if (!ctx->prepared)
-		return 0;
-
 	ret = mipi_dsi_dcs_set_display_off(dsi);
 	if (ret < 0)
 		dev_err(ctx->dev, "failed to set display off: %d\n", ret);
···
 	regulator_disable(ctx->iovcc);
 	regulator_disable(ctx->vci);
 
-	ctx->prepared = false;
-
 	return 0;
 }
 
···
 	struct xpp055c272 *ctx = panel_to_xpp055c272(panel);
 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
 	int ret;
-
-	if (ctx->prepared)
-		return 0;
 
 	dev_dbg(ctx->dev, "Resetting the panel\n");
 	ret = regulator_enable(ctx->vci);
···
 	}
 
 	msleep(50);
-
-	ctx->prepared = true;
 
 	return 0;