Bluetooth: Move set_bredr_scan() to avoid forward declaration

The set_bredr_scan() function will soon be needed by the set_bredr()
function, so move it to a new location to avoid having to add a forward
declaration.

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