Bluetooth: Update link key mgmt APIs to match latest spec.

BR/EDR link keys have their own commands and events (separate from SMP)
and the remove_keys command (previously remove_key) removes keys of any
kind for the specified remote address.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>