netutils/libcoap : patch for parsing error on CoAP over TCP

netutils/libcoap : patch for parsing error on CoAP over TCP

This commit is patch for parsing error on CoAP over TCP
 When parse transport type of TCP header,
 coap_get_tcp_header_type_from_initbyte should be used
 The size used on coap_get_tcp_header_type_from_size means that
 option and payload length except for header and token
 (size = pdu->length - size of header - length of token)

problem 1. Token value is not parsed properly on CoAP over TCP case
 - coap_convert_to_tcp_pdu has bugs to find start potiner of token
problem 2. Code value is not parsed proplery on CoAP over TCP case
 - node->pdu is created accordingly its transport type
 - when coap_get_code called, wrong tranport type is used

Change-Id: Iddec317f797fe5934a1025acc60a3ffe9608c747
Signed-off-by: Jin-Seong Kim <jseong82.kim@samsung.com>