ebpf: fix compatibility with libbpf 1.0+

The current implementation fails to load on a system with
libbpf 1.0 and reports that legacy map definitions in 'maps'
section are not supported by libbpf v1.0+. This commit updates
the Makefile to add BTF (-g flag) and appropriately updates
the maps in rss.bpf.c and update the skeleton file in repo.

Signed-off-by: Shreesh Adiga <16567adigashreesh@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>