selftests/bpf: Adjust selftest due to function rename

selftests/bpf: Adjust selftest due to function rename

do_filp_open() was renamed in commit
541003b576c3 ("rename do_filp_open() to do_file_open()")

This broke test_profiler, because it uses a kretprobe on that
function. Fix it by renaming accordingly.

Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Closes: https://lore.kernel.org/bpf/djwjf2vfb7gro3rfag666bojod6ytcectahnb5z6hx2hawimtj@sx47ghzjg4lw/
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260210235855.215679-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>