kthread: remove incorrect comment in kthread_create_on_cpu()

kthread: remove incorrect comment in kthread_create_on_cpu()

Originally kthread_create_on_cpu() parked and woke up the new thread.
However, since commit a65d40961dc7 ("kthread/smpboot: do not park in
kthread_create_on_cpu()") this is no longer the case.  This patch removes
the comment that has been left behind and is now incorrect / stale.

Fixes: a65d40961dc7 ("kthread/smpboot: do not park in kthread_create_on_cpu()")
Signed-off-by: Ilias Stamatis <stamatis.iliass@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: http://lkml.kernel.org/r/20200611135920.240551-1-stamatis.iliass@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>