net: ethernet: mtk_eth_soc: fix possible memory leak in mtk_probe()

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: mtk_eth_soc: fix possible memory leak in mtk_probe() If mtk_wed_add_hw() has been called, mtk_wed_exit() needs be called in error path or removing module to free the memory allocated in mtk_wed_add_hw().