LWIP: Remove unused MBOX configs

The configs have never been used and LWIP just uses its own settings.

Author: michalpasztamobica

features/lwipstack/lwipopts.h

@@ -84,11 +84,6 @@
 #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
-#define DEFAULT_TCP_RECVMBOX_SIZE   MBED_CONF_LWIP_DEFAULT_TCP_RECVMBOX_SIZE
-#define DEFAULT_UDP_RECVMBOX_SIZE   8
-#define DEFAULT_RAW_RECVMBOX_SIZE   8
-#define DEFAULT_ACCEPTMBOX_SIZE     8
 
 // Thread stacks use 8-byte alignment
 #define LWIP_ALIGN_UP(pos, align) ((pos) % (align) ? (pos) +  ((align) - (pos) % (align)) : (pos))

features/lwipstack/mbed_lib.json

@@ -90,14 +90,6 @@
             "help": "TCP Maximum segment size, see LWIP opt.h for more information. Current default is 536.",
             "value": 536
         },
-        "tcpip-mbox-size": {
-            "help": "TCPIP mailbox size",
-            "value": 8
-        },
-        "default-tcp-recvmbox-size": {
-            "help": "Default TCPIP receive mailbox size",
-            "value": 8
-        },
         "mbox-size": {
             "help": "mailbox size",
             "value": 8