drm/vkms: refactor overlay plane creation

Move the logic to create an overlay plane to its own function.
Refactor, no functional changes.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220107182809.141003-1-jose.exposito89@gmail.com

drivers/gpu/drm/vkms/vkms_output.c

@@ -32,14 +32,29 @@ static const struct drm_connector_helper_funcs vkms_conn_helper_funcs = {
 	.get_modes    = vkms_conn_get_modes,
 };
 
+static int vkms_add_overlay_plane(struct vkms_device *vkmsdev, int index,
+				  struct drm_crtc *crtc)
+{
+	struct vkms_plane *overlay;
+
+	overlay = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_OVERLAY, index);
+	if (IS_ERR(overlay))
+		return PTR_ERR(overlay);
+
+	if (!overlay->base.possible_crtcs)
+		overlay->base.possible_crtcs = drm_crtc_mask(crtc);
+
+	return 0;
+}
+
 int vkms_output_init(struct vkms_device *vkmsdev, int index)
 {
 	struct vkms_output *output = &vkmsdev->output;
 	struct drm_device *dev = &vkmsdev->drm;
 	struct drm_connector *connector = &output->connector;
 	struct drm_encoder *encoder = &output->encoder;
 	struct drm_crtc *crtc = &output->crtc;
-	struct vkms_plane *primary, *cursor = NULL, *overlay = NULL;
+	struct vkms_plane *primary, *cursor = NULL;
 	int ret;
 	int writeback;
 
@@ -48,12 +63,9 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
 		return PTR_ERR(primary);
 
 	if (vkmsdev->config->overlay) {
-		overlay = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_OVERLAY, index);
-		if (IS_ERR(overlay))
-			return PTR_ERR(overlay);
-
-		if (!overlay->base.possible_crtcs)
-			overlay->base.possible_crtcs = drm_crtc_mask(crtc);
+		ret = vkms_add_overlay_plane(vkmsdev, index, crtc);
+		if (ret)
+			return ret;
 	}
 
 	if (vkmsdev->config->cursor) {