Bluetooth: Remove empty event handler

This patch removes the hci_cc_le_set_scan_param event handler. This
handler became empty because failures of this event are now handled
by start_discovery_complete function in mgmt.c.

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>