Add missing sudo for creating symlinks.

This is needed when running mender-convert outside of the docker container.

Changelog: None
Signed-off-by: Drew Moseley <drew.moseley@northern.tech>

mender-convert-modify

@@ -164,9 +164,9 @@ kernel_imagetype=kernel
 initrd_imagetype=initrd
 EOF
 
-  run_and_log_cmd "ln -s ${kernel_imagetype} work/rootfs/boot/kernel"
+  run_and_log_cmd "sudo ln -s ${kernel_imagetype} work/rootfs/boot/kernel"
   if [ "${initrd_imagetype}" != "" ]; then
-    run_and_log_cmd "ln -s ${initrd_imagetype} work/rootfs/boot/initrd"
+    run_and_log_cmd "sudo ln -s ${initrd_imagetype} work/rootfs/boot/initrd"
   fi
 
   # For partuuid support grub.cfg expects dedicated variables to be added