[BSP] Fix compiling error

bsp/lpc176x/rtconfig.h

@@ -149,8 +149,6 @@
 // #define RT_LWIP_SNMP
 // <bool name="RT_LWIP_DHCP" description="Enable DHCP client to get IP address" default="false" />
 // #define RT_LWIP_DHCP
-// <integer name="RT_LWIP_TCP_SEG_NUM" description="the number of simultaneously queued TCP" default="4" />
-#define RT_LWIP_TCP_SEG_NUM	4
 // <integer name="RT_LWIP_TCPTHREAD_PRIORITY" description="the thread priority of TCP thread" default="128" />
 #define RT_LWIP_TCPTHREAD_PRIORITY	12
 // <integer name="RT_LWIP_TCPTHREAD_MBOX_SIZE" description="the mail box size of TCP thread to wait for" default="32" />