net: ethernet: mtk_eth_soc: remove cpu_relax in mtk_pending_work

Get rid of cpu_relax in mtk_pending_work routine since MTK_RESETTING is
set only in mtk_pending_work() and it runs holding rtnl lock

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>