fm10k: Do not assume budget will never be 0 for NAPI

The netpoll path will call napi->poll with a budget of 0 in order to clean
the Tx rings only.  This change updates the fm10k driver so that it will
correctly support that instead of cleaning 1 Rx frame if a budget of 0 is
received.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/fm10k/fm10k_main.c

@@ -610,7 +610,7 @@ static bool fm10k_clean_rx_irq(struct fm10k_q_vector *q_vector,
 	unsigned int total_bytes = 0, total_packets = 0;
 	u16 cleaned_count = fm10k_desc_unused(rx_ring);
 
-	do {
+	while (likely(total_packets < budget)) {
 		union fm10k_rx_desc *rx_desc;
 
 		/* return some buffers to hardware, one at a time is too slow */
@@ -659,7 +659,7 @@ static bool fm10k_clean_rx_irq(struct fm10k_q_vector *q_vector,
 
 		/* update budget accounting */
 		total_packets++;
-	} while (likely(total_packets < budget));
+	}
 
 	/* place incomplete frames back on ring for completion */
 	rx_ring->skb = skb;