Fixed build

Also removed the assert, since we assume window->driverdata is valid everywhere else.

src/video/wayland/SDL_waylandwindow.c

@@ -2470,11 +2470,8 @@ void Wayland_SetWindowSize(SDL_VideoDevice *_this, SDL_Window *window)
 
 void Wayland_GetWindowSizeInPixels(SDL_VideoDevice *_this, SDL_Window *window, int *w, int *h)
 {
-    SDL_WindowData *data;
+    SDL_WindowData *data = window->driverdata;
 
-    SDL_assert(window->driverdata)
-
-    data = window->driverdata;
     *w = data->current.drawable_width;
     *h = data->current.drawable_height;
 }