cfg80211: use wdev in mgmt-tx/ROC APIs

The management frame and remain-on-channel APIs will be
needed in the P2P device abstraction, so move them over
to the new wdev-based APIs. Userspace can still use both
the interface index and wdev identifier for them so it's
backward compatible, but for the P2P Device wdev it will
be able to use the wdev identifier only.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>