esp-pci: fixup deadlock with linux

A linux guest will be issuing messages:

[   32.124042] DC390: Deadlock in DataIn_0: DMA aborted unfinished: 000000 bytes remain!!
[   32.126348] DC390: DataIn_0: DMA State: 0

and the HBA will fail to work properly.
Reason is the emulation is not setting the 'DMA transfer done'
status correctly.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit c3543fb)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

hw/scsi/esp-pci.c

@@ -268,6 +268,8 @@ static void esp_pci_dma_memory_rw(PCIESPState *pci, uint8_t *buf, int len,
     /* update status registers */
     pci->dma_regs[DMA_WBC] -= len;
     pci->dma_regs[DMA_WAC] += len;
+    if (pci->dma_regs[DMA_WBC] == 0)
+        pci->dma_regs[DMA_STAT] |= DMA_STAT_DONE;
 }
 
 static void esp_pci_dma_memory_read(void *opaque, uint8_t *buf, int len)