genetlink: properly support per-op policy dumping

Add support for per-op policy dumping. The data is pretty much
as before, except that now the assumption that the policy with
index 0 is "the" policy no longer holds - you now need to look
at the new CTRL_ATTR_OP_POLICY attribute which is a nested attr
(indexed by op) containing attributes for do and dump policies.

When a single op is requested, the CTRL_ATTR_OP_POLICY will be
added in the same way, since do and dump policies may differ.

Change-Id: I19674e30193a115c120d976d1e3ebc9ec7c8235e
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2 files changed