xen: xenbus: quirk uses x86 specific cpuid

This breaks on ARM. This quirk is not necessary on ARM because no
hypervisors of that vintage exist for that architecture (port is too
new).
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
[v1: Moved the ifdef inside the function per Jan Beulich suggestion]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/xenbus/xenbus_xs.c

@@ -627,6 +627,7 @@ static struct xenbus_watch *find_watch(const char *token)
  */
 static bool xen_strict_xenbus_quirk(void)
 {
+#ifdef CONFIG_X86
 	uint32_t eax, ebx, ecx, edx, base;
 
 	base = xen_cpuid_base();
@@ -634,6 +635,7 @@ static bool xen_strict_xenbus_quirk(void)
 
 	if ((eax >> 16) < 4)
 		return true;
+#endif
 	return false;
 
 }