i40e: Record number of RXes cleaned during NAPI

Adjust i40e_clean_rx_irq to accept an out parameter which records the number of
RX packets cleaned.

No XDP related code is modified and care has been taken to avoid changing
control flow.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>