net/i40e does not report interrupt for the second packet

If I understand Rx interrupts functionality correctly, Rx interrupts should be
generated until disabled. However, it does not happen in the case of i40e with
X710 NIC.

The problem is found by open-source test suite which has been run at UNH IOL
[1].

Scenario is simple:
 - enable Rx interrupts
 - send packet from peer
 - check interrupt, receive packet
 - send one more packet
 - check interrupt - failure, no interupt

[1]
https://ts-factory.io/bublik/v2/log/362398?mode=treeAndlog&focusId=363533&experimental=true&lineNumber=1_69