Fixing ICMP_TYPE_ECHO_REQ and ICMP_TYPE_ECHO_RESP. They were swapped.
According to IANA (https://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml) and RFC792(https://tools.ietf.org/html/rfc792) page 14, the echo Request/Reply constants are swapped, this patch fixes the swap.