error: Don't abuse qemu_error() for non-error in scsi_hot_add()

Commit 30d335d6 converted an informational message from
monitor_printf() to qemu_error(), probably because the latter doesn't
need a mon argument.  A later commit will make qemu_error() print
additional stuff that is only appropriate for proper errors, and then
this will break.  Clean it up.

hw/pci-hotplug.c

@@ -73,7 +73,8 @@ static PCIDevice *qemu_pci_hot_add_nic(Monitor *mon,
     return pci_nic_init(&nd_table[ret], "rtl8139", devaddr);
 }
 
-static int scsi_hot_add(DeviceState *adapter, DriveInfo *dinfo, int printinfo)
+static int scsi_hot_add(Monitor *mon, DeviceState *adapter,
+                        DriveInfo *dinfo, int printinfo)
 {
     SCSIBus *scsibus;
     SCSIDevice *scsidev;
@@ -97,7 +98,8 @@ static int scsi_hot_add(DeviceState *adapter, DriveInfo *dinfo, int printinfo)
     dinfo->unit = scsidev->id;
 
     if (printinfo)
-        qemu_error("OK bus %d, unit %d\n", scsibus->busnr, scsidev->id);
+        monitor_printf(mon, "OK bus %d, unit %d\n",
+                       scsibus->busnr, scsidev->id);
     return 0;
 }
 
@@ -131,7 +133,7 @@ void drive_hot_add(Monitor *mon, const QDict *qdict)
             monitor_printf(mon, "no pci device with address %s\n", pci_addr);
             goto err;
         }
-        if (scsi_hot_add(&dev->qdev, dinfo, 1) != 0) {
+        if (scsi_hot_add(mon, &dev->qdev, dinfo, 1) != 0) {
             goto err;
         }
         break;
@@ -203,7 +205,7 @@ static PCIDevice *qemu_pci_hot_add_storage(Monitor *mon,
         if (qdev_init(&dev->qdev) < 0)
             dev = NULL;
         if (dev && dinfo) {
-            if (scsi_hot_add(&dev->qdev, dinfo, 0) != 0) {
+            if (scsi_hot_add(mon, &dev->qdev, dinfo, 0) != 0) {
                 qdev_unplug(&dev->qdev);
                 dev = NULL;
             }