selftests/bpf: Fix passing arguments via function in test_kmod.sh

Since the tests are run in a function $@ there actually contains the
function arguments, not the script ones.

Pass "$@" to the function as well.

Fixes: 272d1f4c ("selftests: bpf: test_kmod.sh: Pass parameters to the module")
Signed-off-by: Yauheni Kaliuta <ykaliuta@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220926092320.564631-1-ykaliuta@redhat.com