ftgmac100: Fix interrupt status "Packet moved to RX FIFO"

As we don't model the RX or TX FIFO, raise the "Packet moved to RX
FIFO" interrupt status bit as soon as we are handling a RX packet.

Cc: Frederic Konrad <konrad.frederic@yahoo.fr>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Message-Id: <20200819100956.2216690-12-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/net/ftgmac100.c

@@ -950,6 +950,7 @@ static ssize_t ftgmac100_receive(NetClientState *nc, const uint8_t *buf,
         break;
     }
 
+    s->isr |= FTGMAC100_INT_RPKT_FIFO;
     addr = s->rx_descriptor;
     while (size > 0) {
         if (!ftgmac100_can_receive(nc)) {
@@ -1001,8 +1002,6 @@ static ssize_t ftgmac100_receive(NetClientState *nc, const uint8_t *buf,
             /* Last buffer in frame.  */
             bd.des0 |= flags | FTGMAC100_RXDES0_LRS;
             s->isr |= FTGMAC100_INT_RPKT_BUF;
-        } else {
-            s->isr |= FTGMAC100_INT_RPKT_FIFO;
         }
         ftgmac100_write_bd(&bd, addr);
         if (bd.des0 & s->rxdes0_edorr) {