m68k: defconfig: Update defconfigs for v5.8-rc3

  - Re-enable modular build of DES crypto algorithm (no longer
    auto-enabled since commit be013698 ("esp, ah: modernize the
    crypto algorithm selections")),
  - Enable modular build of prime numbers and bitops test modules.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20200615075458.22088-1-geert@linux-m68k.org
Link: https://lore.kernel.org/r/20200706093456.15641-1-geert@linux-m68k.org