mm: kfence: fix elapsed time for allocated/freed track

Fix elapsed time for the allocated/freed track introduced by commit
62e73fd8.

Link: https://lkml.kernel.org/r/20240924085004.75401-1-qiwu.chen@transsion.com


Fixes: 62e73fd8 ("mm: kfence: print the elapsed time for allocated/freed track")
Signed-off-by: qiwu.chen <qiwu.chen@transsion.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>