selftests/bpf: extend changes_pkt_data with cases w/o subprograms

commit 04789af7 upstream.

Extend changes_pkt_data tests with test cases freplacing the main
program that does not have subprograms. Try four combinations when
both main program and replacement do and do not change packet data.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241212070711.427443-2-eddyz87@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>