x86/MCE: adjust ID2COOKIE() for Misra C:2012 rule 11.2

... ("Conversions shall not be performed between a pointer to an
incomplete type and any other type"): Add an intermediate cast to void *.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Nicola Vetrini <nicola.vetrini@bugseng.com>

xen/arch/x86/cpu/mcheck/mce.c

@@ -1264,7 +1264,8 @@ static void cf_check __maybe_unused x86_mc_mceinject(void *data)
 
 #if BITS_PER_LONG == 64
 
-#define ID2COOKIE(id) ((mctelem_cookie_t)(id))
+/* Two layers of casting to cover Misra C:2012 rule 11.2. */
+#define ID2COOKIE(id) ((mctelem_cookie_t)(void *)(id))
 #define COOKIE2ID(c) ((uint64_t)(c))
 
 #elif defined(BITS_PER_LONG)