Fix several doxygen errors all over the code

src/core/dns.c

@@ -1399,6 +1399,12 @@ dns_gethostbyname(const char *hostname, ip_addr_t *addr, dns_found_callback foun
 }
 
 /** Like dns_gethostbyname, but returned address type can be controlled:
+ * @param hostname the hostname that is to be queried
+ * @param addr pointer to a ip_addr_t where to store the address if it is already
+ *             cached in the dns_table (only valid if ERR_OK is returned!)
+ * @param found a callback function to be called on success, failure or timeout (only if
+ *              ERR_INPROGRESS is returned!)
+ * @param callback_arg argument to pass to the callback function
  * @param dns_addrtype: - LWIP_DNS_ADDRTYPE_IPV4_IPV6: try to resolve IPv4 first, try IPv6 if IPv4 fails only
  *                      - LWIP_DNS_ADDRTYPE_IPV6_IPV4: try to resolve IPv6 first, try IPv4 if IPv6 fails only
  *                      - LWIP_DNS_ADDRTYPE_IPV4: try to resolve IPv4 only

src/core/ipv4/autoip.c

@@ -127,7 +127,7 @@ static void autoip_start_probing(struct netif *netif);
  * Using this prevents autoip_start to allocate it using mem_malloc.
  *
  * @param netif the netif for which to set the struct autoip
- * @param dhcp (uninitialised) dhcp struct allocated by the application
+ * @param autoip (uninitialised) autoip struct allocated by the application
  */
 void
 autoip_set_struct(struct netif *netif, struct autoip *autoip)

src/core/pbuf.c

@@ -348,7 +348,7 @@ pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
 #if LWIP_SUPPORT_CUSTOM_PBUF
 /** Initialize a custom pbuf (already allocated).
  *
- * @param layer flag to define header size
+ * @param l flag to define header size
  * @param length size of the pbuf's payload
  * @param type type of the pbuf (only used to treat the pbuf accordingly, as
  *        this function allocates no memory)
@@ -1110,6 +1110,7 @@ pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len)
  * @param buf pbuf to fill with data
  * @param dataptr application supplied data buffer
  * @param len length of the application supplied data buffer
+ * @param offset offset in pbuf where to copy dataptr to
  *
  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
  */

src/core/tcp_out.c

@@ -745,8 +745,6 @@ memerr:
  *
  * @param pcb Protocol control block for the TCP connection.
  * @param flags TCP header flags to set in the outgoing segment.
- * @param optdata pointer to TCP options, or NULL.
- * @param optlen length of TCP options in bytes.
  */
 err_t
 tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)