TCP Read-Ahead: Convert to use I/O buffer chains

configs/cloudctrl/nsh/defconfig

@@ -404,8 +404,6 @@ CONFIG_NET_TCP=y
 CONFIG_NET_TCP_CONNS=40
 CONFIG_NET_MAX_LISTENPORTS=40
 CONFIG_NET_TCP_READAHEAD=y
-CONFIG_NET_TCP_READAHEAD_BUFSIZE=536
-CONFIG_NET_NTCP_READAHEAD_BUFFERS=16
 CONFIG_NET_TCP_RECVDELAY=0
 CONFIG_NET_TCPBACKLOG=y
 CONFIG_NET_UDP=y
@@ -420,6 +418,11 @@ CONFIG_NET_STATISTICS=y
 CONFIG_NET_RECEIVE_WINDOW=536
 CONFIG_NET_ARPTAB_SIZE=16
 # CONFIG_NET_ARP_IPIN is not set
+CONFIG_NET_IOB=y
+CONFIG_IOB_NBUFFERS=24
+CONFIG_IOB_BUFSIZE=196
+CONFIG_IOB_NCHAINS=8
+CONFIG_IOB_THROTTLE=0
 
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