net: ethernet: mtk_eth_soc: increase DMA ring sizes

256 descriptors is not enough for multi-gigabit traffic under load on
MT7622. Bump it to 512 to improve performance.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.h

@@ -22,7 +22,7 @@
 #define MTK_MAX_RX_LENGTH	1536
 #define MTK_MAX_RX_LENGTH_2K	2048
 #define MTK_TX_DMA_BUF_LEN	0x3fff
-#define MTK_DMA_SIZE		256
+#define MTK_DMA_SIZE		512
 #define MTK_NAPI_WEIGHT		64
 #define MTK_MAC_COUNT		2
 #define MTK_RX_ETH_HLEN		(ETH_HLEN + ETH_FCS_LEN)