egl/wayland: fix memory leak in error handling case

Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29990>

src/egl/wayland/wayland-drm/wayland-drm.c

@@ -86,6 +86,7 @@ create_buffer(struct wl_client *client, struct wl_resource *resource,
    if (buffer->driver_buffer == NULL) {
       wl_resource_post_error(resource, WL_DRM_ERROR_INVALID_NAME,
                              "invalid name");
+      free(buffer);
       return;
    }