Revert "usbtmc: convert to devm_kzalloc"

This reverts commit e6c7efdc.

Turns out it was totally wrong.  The memory is supposed to be bound to
the kref, as the original code was doing correctly, not the
device/driver binding as the devm_kzalloc() would cause.

This fixes an oops when read would be called after the device was
unbound from the driver.
Reported-by: Ladislav Michl <ladis@linux-mips.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable <stable@vger.kernel.org>  # 3.12+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/usbtmc.c

@@ -141,6 +141,7 @@ static void usbtmc_delete(struct kref *kref)
 	struct usbtmc_device_data *data = to_usbtmc_data(kref);
 
 	usb_put_dev(data->usb_dev);
+	kfree(data);
 }
 
 static int usbtmc_open(struct inode *inode, struct file *filp)
@@ -1379,7 +1380,7 @@ static int usbtmc_probe(struct usb_interface *intf,
 
 	dev_dbg(&intf->dev, "%s called\n", __func__);
 
-	data = devm_kzalloc(&intf->dev, sizeof(*data), GFP_KERNEL);
+	data = kmalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;