ramips: ethernet: turn off flow control

Several users have been reporting crashing issues with the ethernet
driver.

One source says that this is a silicon bug in mt7621:
openwrt/mt76#211 (comment)

A user that has been testing this has seen greater than 2-3 days uptime
of the ethernet interface with this change:
https://forum.openwrt.org/t/mtk-soc-eth-watchdog-timeout-after-r11573/50000/12

Signed-off-by: Rosen Penev <rosenp@gmail.com>

target/linux/ramips/files/drivers/net/ethernet/mediatek/gsw_mt7621.c

@@ -98,8 +98,8 @@ static void mt7621_hw_init(struct mt7620_gsw *gsw, struct device_node *np)
 	mt7530_mdio_w32(gsw, 0x7000, 0x3);
 	usleep_range(10, 20);
 
-	if ((rt_sysc_r32(SYSC_REG_CHIP_REV_ID) & 0xFFFF) == 0x0101) {
-		/* (GE1, Force 1000M/FD, FC ON, MAX_RX_LENGTH 1536) */
+	if ((rt_sysc_r32(SYSC_REG_CHIP_REV_ID) & 0xFFFF) >= 0x0101) {
+		/* (GE1, Force 1000M/FD, FC OFF, MAX_RX_LENGTH 1536) */
 		mtk_switch_w32(gsw, 0x2305e30b, GSW_REG_MAC_P0_MCR);
 		mt7530_mdio_w32(gsw, 0x3600, 0x5e30b);
 	} else {