Bluetooth: During le_conn_timeout disable EXT_ADV

Disabling LE_LEGACY_ADV when LE_EXT_ADV is enabled causes 'command
disallowed . This patch fixes that issue and disables EXT_ADV if
enabled.

Signed-off-by: Sathish Narsimman <sathish.narasimman@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>