net: ethernet: mtk_eth_soc: fix memory corruption during fq dma init

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: mtk_eth_soc: fix memory corruption during fq dma init The loop responsible for allocating up to MTK_FQ_DMA_LENGTH buffers must only touch as many descriptors, otherwise it ends up corrupting unrelated memory. Fix the loop iteration count accordingly.