kernel: Deactivate CONFIG_BINFMT_MISC

kernel: Deactivate CONFIG_BINFMT_MISC

CONFIG_BINFMT_MISC allows it to add support for new executable formats
to the kernel from user space, the kernel will then detect for example a
java binary and call the java execution program automatically. I am not
aware that this feature is used in OpenWrt and this could be used to
exploit something. Deactivate it for all targets for now.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>