Parse extra un-used TcpInfo

Parse tcp info only until tcpi_sndbuf_limited now. If device
kernel version >= 4.18, there will be some un-parsed bytes left
because the tcp_info struct was expanded. Skip the remaining
un-parsed part.

Bug: 145275899
Bug: 145328512
Test: atest NetworkStackTests NetworkStackNextTests
Change-Id: I56aa6be183b8b804898926dae2c47a497c49f893