do not set phys_id in ethtool_ops

since 1ab7b6ac2709d0eb05a7144cd0e14faa3a7ea162 in linux-2.6.git,
ethtool_ops does not include phys_id anymore.
stop setting it and remove the function used for that.
don't hardcode paths to binaries

on Debian, Ubuntu and maybe others, lspci/setpci are in /usr/bin
and not in /sbin. stop hardcoding the paths, the shell will find
the correct binary.

while at it, don't hardcode ifconfig either, even if it actually
is in /sbin
properly link to ncurses
allow overriding the kernel version to build for by passing a KVER