security/keys: add CONFIG_KEYS_COMPAT to Kconfig

security/keys: add CONFIG_KEYS_COMPAT to Kconfig

CONFIG_KEYS_COMPAT is defined in arch-specific Kconfigs and is missing for
several 64-bit architectures : mips, parisc, tile.

At the moment and for those architectures, calling in 32-bit userspace the
keyctl syscall would return an ENOSYS error.

This patch moves the CONFIG_KEYS_COMPAT option to security/keys/Kconfig, to
make sure the compatibility wrapper is registered by default for any 64-bit
architecture as long as it is configured with CONFIG_COMPAT.

[DH: Modified to remove arm64 compat enablement also as requested by Eric
 Biggers]

Signed-off-by: Bilal Amarni <[email protected]>
Signed-off-by: David Howells <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
cc: Eric Biggers <[email protected]>
Signed-off-by: James Morris <[email protected]>