selftsets/bpf: Retry map update for non-preallocated per-cpu map

BPF CI failed due to map_percpu_stats_percpu_hash from time to time [1].
It seems that the failure reason is per-cpu bpf memory allocator may not
be able to allocate per-cpu pointer successfully and it can not refill
free llist timely, and bpf_map_update_elem() will return -ENOMEM.

So mitigate the problem by retrying the update operation for
non-preallocated per-cpu map.

[1]: https://github.com/kernel-patches/bpf/actions/runs/6713177520/job/18244865326?pr=5909



Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231101032455.3808547-4-houtao@huaweicloud.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>