OUTPUT_FORMAT is known within Kconfig, so we can use the same
"elf64-x86-64" specific logic when setting the defaults for
CONFIG_KASAN_SHADOW_OFFSET and CONFIG_KASAN_SHADOW_SIZE.
The LKL_HOST_CONFIG_KASAN_SHADOW_OFFSET/_SIZE autoconf variables appear
to be unused, so drop them for now. If necessary we could put them back
in arch/lkl/include/generated/uapi/asm/config.h .
Signed-off-by: David Disseldorp <ddiss@suse.de>