usb: musb_debugfs: don't use the struct file private_data field with seq_files

seq_files use the private_data field of a file struct for storing a seq_file structure,
data should be stored in seq_file's own private field (e.g. file->private_data->private)
Otherwise seq_release() will free the private data when the file is closed.

Signed-off-by: Mathias Nyman <mathias.nyman@nokia.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/musb_debugfs.c

@@ -195,15 +195,14 @@ static const struct file_operations musb_regdump_fops = {
 
 static int musb_test_mode_open(struct inode *inode, struct file *file)
 {
-	file->private_data = inode->i_private;
-
 	return single_open(file, musb_test_mode_show, inode->i_private);
 }
 
 static ssize_t musb_test_mode_write(struct file *file,
 		const char __user *ubuf, size_t count, loff_t *ppos)
 {
-	struct musb		*musb = file->private_data;
+	struct seq_file		*s = file->private_data;
+	struct musb		*musb = s->private;
 	u8			test = 0;
 	char			buf[18];