Merge branch 'fix-bpf-docs'

Quentin Monnet says:

====================
Hi,
This set is an update to the documentation for the BPF helper functions in
the UAPI header bpf.h, used to generate the bpf-helpers(7) man page.

First patch contains fixes to the current documentation. The second patch
adds documentation for the two helpers bpf_spin_lock() and
bpf_spin_unlock(). The last patch simply reports the changes to the version
of that header in tools/.
====================

Signed-off-by: Alexei Starovoitov <[email protected]>