m68k: defconfig: Update defconfigs for v6.16-rc2

  - Enable modular build of the SCTP network protocol (no longer
    auto-enabled since now commit 6f8b4788 ("dlm: drop SCTP
    Kconfig dependency")),
  - Enable modular build of OpenVPN data channel offload,
  - Enable modular build of Btrfs and XFS filesystem support, and
    Universal TUN/TAP device driver support (no longer auto-enabled
    since commit 92f3c5a0 ("lib/test_kmod: do not
    hardcode/depend on any filesystem")),
  - Enable modular build of Null crypto algorithms (no longer
    auto-enabled since commit 0c08c729 ("crypto: krb5enc - do
    not select CRYPTO_NULL")),
  - Drop CONFIG_CRYPTO_CHACHA20POLY1305=m (selected by OVPN),
  - Enable modular build of the simple prime number generator for
    testing (no longer auto-enabled since commit 3f292517
    ("lib/prime_numbers: KUnit test should not select PRIME_NUMBERS")),
  - Enable the benchmark in the (modular) KUnit tests for CRC functions.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/365889e04f7289fdcb393911c18639486a0d3e73.1750102111.git.geert@linux-m68k.org