Merge branch 'bpf-cpumap-improve-error-propagation-in-cpu_map_update_elem'

Kohei Enju says:

====================
bpf: cpumap: improve error propagation in cpu_map_update_elem()

This series improves error propagation in cpumap and adds selftests that
cover the failure cases.

Currently, failures returned from __cpu_map_entry_alloc() are ignored
and always converted to -ENOMEM by cpu_map_update_elem(). This series
ensures the correct error propagation and adds selftests.

Changes:
  v2:
    - send to bpf-next, not to bpf
    - drop Fixes: tag
  v1: https://lore.kernel.org/bpf/20251128160504.57844-1-enjuk@amazon.com/
====================

Link: https://patch.msgid.link/20251208131449.73036-1-enjuk@amazon.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>