xilinx_axidma: Fix debug mode compile messages

Missing cast one one of the conditionally compiled printfs.
Signed-off-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/xilinx_axidma.c

@@ -444,7 +444,7 @@ static void axidma_write(void *opaque, hwaddr addr,
             break;
         default:
             D(qemu_log("%s: ch=%d addr=" TARGET_FMT_plx " v=%x\n",
-                  __func__, sid, addr * 4, value));
+                  __func__, sid, addr * 4, (unsigned)value));
             s->regs[addr] = value;
             break;
     }