Fixed a malformed if else
Fixed a malformed if else

Cause 
```
$customerReference = $customerData['adyen_customer_ref']
						?: $customerData['increment_id']
						?: $customerId;
```
would never have worked
Adyen/magento,Adyen/magento,Adyen/magento,Adyen/adyen-magento,Adyen/adyen-magento,Adyen/adyen-magento