Bluetooth: Remove bt_hci_reset() API

There's no clear need for this API (at least for now) and supporting
it means we really need to get all state cleanup procedures correct.
Remove it for now.

Change-Id: Ia2c7d51d410117bef12bc08f4f97a4e38ccfb77a
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
3 files changed