net: broadcom: bcm4908_enet: enable RX after processing packets

When receiving a lot of packets hardware may run out of free
descriptiors and stop RX ring. Enable it every time after handling
received packets.

Fixes: 4feffeadbc ("net: broadcom: bcm4908enet: add BCM4908 controller driver")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210226132038.29849-1-zajec5@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/broadcom/bcm4908_enet.c

@@ -592,6 +592,9 @@ static int bcm4908_enet_poll(struct napi_struct *napi, int weight)
 		bcm4908_enet_intrs_on(enet);
 	}
 
+	/* Hardware could disable ring if it run out of descriptors */
+	bcm4908_enet_dma_rx_ring_enable(enet, &enet->rx_ring);
+
 	return handled;
 }