There are several situations where we're interested in knowing whether
we're currently in the process of powering off an adapter. This patch
adds a convenience function for the purpose and makes it public since
we'll soon need to access it from hci_event.c as well.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>