auxdisplay: Convert list_for_each to entry variant

convert list_for_each() to list_for_each_entry() where
applicable.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>