Merge branch 'ioam-insert-freq' into next

Justin Iurman  says:

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

The insertion frequency is represented as "k/n", meaning IOAM will be
added to "k" packets over "n" packets, with 0 < k <= n <= 1000000.
Therefore, it provides the following range of insertion frequencies:
[0.0001% ... 100%].

Default frequency is "1/1" (i.e., applied to all packets) for backward
compatibility.

Previous command:
ip -6 ro ad fc00::1/128 encap ioam6 mode ...

New command:
ip -6 ro ad fc00::1/128 encap ioam6 [ freq k/n ] mode ...

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

Signed-off-by: David Ahern <dsahern@kernel.org>