tools headers: kcfi: rename missed CONFIG_CFI_CLANG

Commit 23ef9d4 ("kcfi: Rename CONFIG_CFI_CLANG to CONFIG_CFI")
missed one instance of CONFIG_CFI_CLANG. Rename it to match the original
kernel header. This addresses the following build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/linux/cfi_types.h include/linux/cfi_types.h

Cc: Kees Cook <kees@kernel.org>
Fixes: a5ba183 ("Merge tag 'hardening-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux")
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20251006225148.1636486-1-cmllamas@google.com
Signed-off-by: Kees Cook <kees@kernel.org>

Author: Carlos Llamas

tools/include/linux/cfi_types.h

@@ -43,7 +43,7 @@
 
 #else /* __ASSEMBLY__ */
 
-#ifdef CONFIG_CFI_CLANG
+#ifdef CONFIG_CFI
 #define DEFINE_CFI_TYPE(name, func)						\
 	/*									\
 	 * Force a reference to the function so the compiler generates		\