net: stmmac: xgmac: Add RBU handling in DMA interrupt

Add the handling of Receive Buffer Unavailable interrupt in the DMA
handler of XGMAC cores.
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c

@@ -322,6 +322,10 @@ static int dwxgmac2_dma_interrupt(void __iomem *ioaddr,
 
 	/* ABNORMAL interrupts */
 	if (unlikely(intr_status & XGMAC_AIS)) {
+		if (unlikely(intr_status & XGMAC_RBU)) {
+			x->rx_buf_unav_irq++;
+			ret |= handle_rx;
+		}
 		if (unlikely(intr_status & XGMAC_TPS)) {
 			x->tx_process_stopped_irq++;
 			ret |= tx_hard_error;