ia64: Fixup asm/cmpxchg.h

From: David Howells <[email protected]>

Empty asm/cmpxchg.h file that was provided as a temporary build fix for the asm/system.h disintgration build problem should really include <asm/intrinsics.h> to make definitions of xchg() and cmpxchg() available.

---

index 507c66c..4c96187 100644
@@ -1 +1 @@
-/* Future home of xchg() and cmpxchg() */
+#include <asm/intrinsics.h>