adjust paths for bpfloader change

that puts tethering mainline module maps and programs
under /sys/fs/bpf/tethering

Test: builds, boots, atest, TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I845cabde74c310c8a4c93b6f040b69ebd05322ab