Before checking if the image is a valid value, we need to check if the
list of items is big enough or we will raise an exception.
Reported-by: Lauren Post <lauren.post@freescale.com>
(From OE-Core rev: b833837cac377e7c1c3ff18531b152340b669329)
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>