mainline inclusion
from mainline-5.13-rc1
commit b3278099
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b3278099b2f6e81771c6c2b70fcf9a56e9ba5d93

-------------------------------------------------

The API gives access to inner map for map in map types (array or
hash of map). It will be used to dynamically set max_entries in it.
Signed-off-by: NYauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210408061310.95877-7-yauheni.kaliuta@redhat.com
(cherry picked from commit b3278099)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>