Disable the ICMP Timestamp reply function in APV

Since the ATCP thread sends the ICMP Timestamp Request packet to both the netisr thread and the Linux kernel, two reply packets are generated.
To fix this problem, I applied two methods:
Revised the code in ATCP to disable the reply function.
Added an iptables rule in the startup configuration to drop ICMP Timestamp Reply packets generated by the Linux kernel.