BUILD: debug: fix build issue on 32-bit platforms in "debug dev task"

Commit 986798718 ("DEBUG: cli: add "debug dev task" to show/wake/expire/kill
tasks and tasklets") caused a build failure on 32-bit platforms when parsing
the task's pointer. Let's use strtoul() and not strtoll(). No backport is
needed, unless the commit above gets backported.
1 file changed