Split _lkpi_iv_key_set_delete() up into set and delete versions as
they are called from net80211.
Add mappings of flags between LinuxKPI and net80211 so we can
take appropriate (non-)action in net80211.
There are more flags to map at a later point for other bits.
Will will also need sort out the one which doesn't map 1:1.
MFC after: 3 days