Revert "selftests/bpf: Add test for bpf_timer overwriting crash"

Revert "selftests/bpf: Add test for bpf_timer overwriting crash"

This reverts commit b0028e1cc1faf2e5d88ad4065590aca90d650182 which is
commit a7e75016a0753c24d6c995bc02501ae35368e333 upstream.

It will break the bpf self-tests build with:
progs/timer_crash.c:8:19: error: field has incomplete type 'struct bpf_timer'
        struct bpf_timer timer;
                         ^
/home/ubuntu/linux/tools/testing/selftests/bpf/tools/include/bpf/bpf_helper_defs.h:39:8:
note: forward declaration of 'struct bpf_timer'
struct bpf_timer;
       ^
1 error generated.

This test can only be built with 5.17 and newer kernels.

Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>