We can't guarantee vmlinuz anymore. Use KERNEL_IMAGETYPE instead.
(From OE-Core rev: cceb4266f3e70382e171c3a338c10d9730c9dc3f)
Signed-off-by: California Sullivan <california.l.sullivan@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>