Add tunnel source ip field in "struct bpf_tunnel_key". Add related code
to set and get tunnel source field.
Signed-off-by: NKaixi Fan <fankaixi.li@bytedance.com>
Link: https://lore.kernel.org/r/20220430074844.69214-2-fankaixi.li@bytedance.comSigned-off-by: NAlexei Starovoitov <ast@kernel.org>