Bluetooth: Convert le_scan_disable timeout to hci_sync

The le_scan_disable timeout was being performed on the deprecated
hci_request.c mechanism.  This timeout is performed in hci_sync.c

Signed-off-by: Brian Gix <brian.gix@intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>