kernel: Deactivate CONFIG_COMPAT

kernel: Deactivate CONFIG_COMPAT

This deactivates the CONFIG_COMPAT kernel option.
With CONFIG_COMPAT the kernel will provide syscall interfaces for arm32
binaries in addition to the interfaces needed for arm64 binaries.

In OpenWrt the complete userspace is compiled for this specific
architecture and support for 32 bit ARM applications is not needed.
This reduces the size and the attack surface for the systems.

On all other targets CONFIG_COMPAT is already deactivated.

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