ACPI: prune undue ia64 leftover

This undoes the part of 3b0246ea03 ("Fix ia64 tools build") which was
missed by e567964a54 ("tools: drop ia64 support").

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/include/acpi/platform/acenv.h

@@ -136,9 +136,7 @@
 
 /*! [Begin] no source code translation */
 
-#if defined(__XEN_TOOLS__) && defined(__ia64__)
-#include "ac_ia64_tools.h"
-#elif 1 /*defined(_LINUX) || defined(__linux__)*/
+#if 1 /*defined(_LINUX) || defined(__linux__)*/
 #include "aclinux.h"
 
 #elif defined(_AED_EFI)