genimage: fix the order of the kernel files in making bootcheckum

Ostree bootchecksum is calculated from four files, they are standard
kernel image, rt kernel image, vmlinuz and initramfs file. Different
order makes different checksum value.

WRCP's INSVC patch does not touch kernel images or initramfs file
while it requires a fixed bootchecksum value. So fix the order as
standard kernel, rt kernel, vmlinuz and initramfs.

Here "kernels" is a list contains standard kernel and then rt kernel.
Remove line "kernels = set(kernels)" to avoid the randomization of
their order.

Signed-off-by: Zhang Xiao <xiao.zhang@windriver.com>

recipes-support/genimage/files/genimage/genimage.py

@@ -862,7 +862,6 @@ def _do_rootfs_post(self, rootfs=None):
         if self.data.get('multiple-kernels'):
             for ks in self.data.get('multiple-kernels').split():
                 kernels.extend(glob.glob(ks, root_dir=os.path.join(rootfs.target_rootfs, "boot/")))
-            kernels = set(kernels)
             os.environ['OSTREE_MULTIPLE_KERNELS'] = ' '.join(kernels) if kernels else ''
         logger.debug("kernels %s", kernels)