1. Fixing astyle and docs
2. Extra mutex lock was removed
3. Bytes are updated when send/recv > 0 and not in case of -ve error
4. Review comments
5. Guard statistics implementation in test with MBED_NW_STATS_ENABLED
From lowercase to uppercase and drops 'test_'-prefix. Test case
descriptions do also match to TC names now.
Additionally all the TCs are not behing MBED_EXTENDED_TESTS
anymore.
Starts splitting Greentea test suites to TCP and UDP suites and adds
more test cases like
tcpsocket_echotest_burst
tcpsocket_echotest_burst_nonblock
tcpsocket_endpoint_close
tcpsocket_recv_100k
tcpsocket_recv_100k
tcpsocket_recv_timeout
tcpsocket_send_timeout
tcpsocket_thread_per_socket_safety
udpsocket_echotest_burst
udpsocket_echotest_burst_nonblock
udpsocket_recv_timeout
udpsocket_sendto_timeout