m68k: defconfig: Update defconfigs for v5.15-rc1

  - Enable modular build of the new MCTP networking core protocol,
  - Enable modular build of the new NTFS Read-Write file system support
    (incl. external compressions lzx/xpress),
  - Enable modular build of the MD4 digest algorithm (no longer
    auto-selected since commit 42c21973 ("cifs: create a MD4
    module and switch cifs.ko to use it")),
  - Move CONFIG_STRING_SELFTEST=m (moved in commit b2ff70a0
    ("lib/test_string.c: move string selftest in the Runtime Testing
    menu")).
  - Drop CONFIG_TEST_SORT=m (auto-enabled since commit 36f33b56
    ("lib/test: convert test_sort.c to use KUnit")).

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20210914073034.3883338-1-geert@linux-m68k.org