mfd: ab8500-debugfs: Fix a typo ("deubgfs")

"debugfs" was misspelled.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/ab8500-debugfs.c

@@ -2587,7 +2587,7 @@ static ssize_t ab8500_unsubscribe_write(struct file *file,
 }
 
 /*
- * - several deubgfs nodes fops
+ * - several debugfs nodes fops
  */
 
 static const struct file_operations ab8500_bank_fops = {