Bluetooth: hci_sync: Convert MGMT_OP_SET_FAST_CONNECTABLE

This creates a synchronized Write Fast Connectable call and attaches it
to the MGMT_OP_SET_FAST_CONNECTABLE management opcode.

Signed-off-by: Brian Gix <brian.gix@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>