drm/panel/raspberrypi: Use refcounted allocation in place of devm_kzalloc()

Move to using the new API devm_drm_panel_alloc() to allocate the
panel. In the call to the new API, avoid using explicit type and use
__typeof() for more type safety.

Signed-off-by: Anusha Srivatsa <asrivats@redhat.com>
Link: https://lore.kernel.org/r/20250710-b4-driver-convert-last-part-july-v1-2-de73ba81b2f5@redhat.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

Author: anushasrivats

drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c

@@ -373,9 +373,12 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c)
 		.node = NULL,
 	};
 
-	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
-	if (!ts)
-		return -ENOMEM;
+	ts = devm_drm_panel_alloc(dev, __typeof(*ts), base,
+				  &rpi_touchscreen_funcs,
+				  DRM_MODE_CONNECTOR_DSI);
+
+	if (IS_ERR(ts))
+		return PTR_ERR(ts);
 
 	i2c_set_clientdata(i2c, ts);
 
@@ -428,9 +431,6 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c)
 		return PTR_ERR(ts->dsi);
 	}
 
-	drm_panel_init(&ts->base, dev, &rpi_touchscreen_funcs,
-		       DRM_MODE_CONNECTOR_DSI);
-
 	/* This appears last, as it's what will unblock the DSI host
 	 * driver's component bind function.
 	 */