tools: bpftool: improve architecture detection by using ifindex

The current architecture detection method in bpftool is designed for host
case.

For offload case, we can't use the architecture of "bpftool" itself.
Instead, we could call the existing "ifindex_to_name_ns" to get DEVNAME,
then read pci id from /sys/class/dev/DEVNAME/device/vendor, finally we map
vendor id to bfd arch name which will finally be used to select bfd backend
for the disassembler.

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>