In order to use HCI request framework in start_discovery, we'll need
to call inquiry_cache_flush in mgmt.c. Therefore, this patch adds the
hci_ prefix to inquiry_cache_flush and makes it non-static.
Signed-off-by: Andre Guedes <andre.guedes@openbossa.org> Acked-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>