Bluetooth: mgmt: Move status parameters into the cmd_complete header

Instead of having status paramters part of each individual command
response it's simpler to just have the status as part of the command
complete header. This patch updates the code to follow this convention
and thereby also ensures compliance with the latest mgmt API
specification.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>