Incorporate review comments from @kjbracey-arm

Author: balajicyp

features/lwipstack/LWIPStack.cpp

@@ -238,7 +238,7 @@ nsapi_error_t LWIP::socket_open(nsapi_socket_t *handle, nsapi_protocol_t proto)
     } else if (proto == NSAPI_ICMP) {
         netconntype = NETCONN_RAW;
     } else {
-        return NSAPI_ERROR_PROTO_UNKNOWN;
+        return NSAPI_ERROR_UNSUPPORTED;
     }
 
 #if LWIP_IPV6

features/lwipstack/lwipopts.h

@@ -81,7 +81,7 @@
 
 #define SYS_LIGHTWEIGHT_PROT        1
 
-#define LWIP_RAW                    MBED_CONF_LWIP_RAWIPSOCKET_ENABLED
+#define LWIP_RAW                    MBED_CONF_LWIP_RAW_SOCKET_ENABLED
 
 #define MEMP_NUM_TCPIP_MSG_INPKT    MBED_CONF_LWIP_MEMP_NUM_TCPIP_MSG_INPKT
 #define TCPIP_MBOX_SIZE             MBED_CONF_LWIP_TCPIP_MBOX_SIZE