scripts/gdb: timerlist: convert int chunks to str

join() expects strings but integers are given.

Convert chunks list to strings before passing it to join()

Link: https://lkml.kernel.org/r/20230406221217.1585486-4-f.fainelli@gmail.com
Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
Signed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>