ART: Do not define abstract HIR kinds.

They were never used and the two cases in HSchedulerARM64's
IsSchedulable() were unreachable.

Test: Rely on TreeHugger.
Change-Id: I506bc2a89a6fbf556f32e25ecfe61eaad236a40a
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 3433e91..1d913c0 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -1956,7 +1956,7 @@
  public:
 #define DECLARE_KIND(type, super) k##type,
   enum InstructionKind {
-    FOR_EACH_INSTRUCTION(DECLARE_KIND)
+    FOR_EACH_CONCRETE_INSTRUCTION(DECLARE_KIND)
     kLastInstructionKind
   };
 #undef DECLARE_KIND