net: ethernet: mtk_ppe: avoid NULL deref when gmac0 is disabled

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: mtk_ppe: avoid NULL deref when gmac0 is disabled If the gmac0 is disabled, the precheck for a valid ingress device will cause a NULL pointer deref and crash the system. This happens because eth->netdev[0] will be NULL but the code will directly try to access netdev_ops. Instead of just checking for the first net_device, it must be checked if any of the mtk_eth net_devices is matching the netdev_ops of the ingress device.