Merge branch 'bpf: Use bpf_mem_cache_alloc/free in bpf_local_storage'

Martin KaFai Lau says:

====================

From: Martin KaFai Lau <martin.lau@kernel.org>

This set is a continuation of the effort in using
bpf_mem_cache_alloc/free in bpf_local_storage [1]

Major change is only using bpf_mem_alloc for task and cgrp storage
while sk and inode stay with kzalloc/kfree. The details is
in patch 2.

[1]: https://lore.kernel.org/bpf/20230308065936.1550103-1-martin.lau@linux.dev/

v3:
- Only use bpf_mem_alloc for task and cgrp storage.
- sk and inode storage stay with kzalloc/kfree.
- Check NULL and add comments in bpf_mem_cache_raw_free() in patch 1.
- Added test and benchmark for task storage.

v2:
- Added bpf_mem_cache_alloc_flags() and bpf_mem_cache_raw_free()
  to hide the internal data structure of the bpf allocator.
- Fixed a typo bug in bpf_selem_free()
- Simplified the test_local_storage test by directly using
  err returned from libbpf
====================

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