m68k: defconfig: Update defconfigs for v5.6-rc4

  - Drop CONFIG_NETFILTER_XT_MATCH_PHYSDEV=m (depends on
    BRIDGE_NETFILTER, which is disabled by default since commit
    98bda63e ("net: disable BRIDGE_NETFILTER by default")),
  - Enable modular build of the WireGuard secure network tunnel,
  - Drop CONFIG_CRYPTO_LIB_{BLAKE2S,CHACHA20POLY1305,CURVE25519}=m
    (auto-enabled by CONFIG_WIREGUARD).

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