net: ethernet: mtk_eth_soc: fix NULL pointer on hw reset

When a hardware reset is triggered on devices not initializing WED the
calls to mtk_wed_fe_reset and mtk_wed_fe_reset_complete dereference a
pointer on uninitialized stack memory.
Break out of both functions in case a hw_list entry is 0.

Fixes: 08a764a7 ("net: ethernet: mtk_wed: add reset/reset_complete callbacks")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/5465c1609b464cc7407ae1530c40821dcdf9d3e6.1692634266.git.daniel@makrotopia.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_wed.c

@@ -221,9 +221,13 @@ void mtk_wed_fe_reset(void)
 
 	for (i = 0; i < ARRAY_SIZE(hw_list); i++) {
 		struct mtk_wed_hw *hw = hw_list[i];
-		struct mtk_wed_device *dev = hw->wed_dev;
+		struct mtk_wed_device *dev;
 		int err;
 
+		if (!hw)
+			break;
+
+		dev = hw->wed_dev;
 		if (!dev || !dev->wlan.reset)
 			continue;
 
@@ -244,8 +248,12 @@ void mtk_wed_fe_reset_complete(void)
 
 	for (i = 0; i < ARRAY_SIZE(hw_list); i++) {
 		struct mtk_wed_hw *hw = hw_list[i];
-		struct mtk_wed_device *dev = hw->wed_dev;
+		struct mtk_wed_device *dev;
+
+		if (!hw)
+			break;
 
+		dev = hw->wed_dev;
 		if (!dev || !dev->wlan.reset_complete)
 			continue;