m68k: Kconfig.debug: Replace single quotes

Replace single quotes in strings with double quotes to match the majority
of the rest of the kernel's Kconfig files.

Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Link: https://lore.kernel.org/r/20220524075848.21684-3-juergh@canonical.com


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>