usb: storage: fix runtime pm issue in usb_stor_probe2

Since commit 71723f95 "PM / runtime: print error when activating a
child to unactive parent" I see the following error message:

scsi host2: usb-storage 1-3:1.0
scsi host2: runtime PM trying to activate child device host2 but parent
	    (1-3:1.0) is not active

Digging into it it seems to be related to the problem described in the
commit message for cd998ded "i2c: designware: Prevent runtime
suspend during adapter registration" as scsi_add_host also calls
device_add and after the call to device_add the parent device is
suspended.

Fix this by using the approach from the mentioned commit and getting
the runtime pm reference before calling scsi_add_host.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/storage/usb.c

@@ -1070,17 +1070,17 @@ int usb_stor_probe2(struct us_data *us)
 	result = usb_stor_acquire_resources(us);
 	if (result)
 		goto BadDevice;
+	usb_autopm_get_interface_no_resume(us->pusb_intf);
 	snprintf(us->scsi_name, sizeof(us->scsi_name), "usb-storage %s",
 					dev_name(&us->pusb_intf->dev));
 	result = scsi_add_host(us_to_host(us), dev);
 	if (result) {
 		dev_warn(dev,
 				"Unable to add the scsi host\n");
-		goto BadDevice;
+		goto HostAddErr;
 	}
 
 	/* Submit the delayed_work for SCSI-device scanning */
-	usb_autopm_get_interface_no_resume(us->pusb_intf);
 	set_bit(US_FLIDX_SCAN_PENDING, &us->dflags);
 
 	if (delay_use > 0)
@@ -1090,6 +1090,8 @@ int usb_stor_probe2(struct us_data *us)
 	return 0;
 
 	/* We come here if there are any problems */
+HostAddErr:
+	usb_autopm_put_interface_no_suspend(us->pusb_intf);
 BadDevice:
 	usb_stor_dbg(us, "storage_probe() failed\n");
 	release_everything(us);