Revert "Disable jit for ARM 64 bit"

Bug: 17950037

This reverts commit bf9026d3e09b5b92b1d94a8e1e3953bf13127bef.
diff --git a/runtime/jit/jit.cc b/runtime/jit/jit.cc
index 82b7ba7..729791f 100644
--- a/runtime/jit/jit.cc
+++ b/runtime/jit/jit.cc
@@ -32,9 +32,6 @@
 namespace jit {
 
 JitOptions* JitOptions::CreateFromRuntimeArguments(const RuntimeArgumentMap& options) {
-  if (kRuntimeISA == kArm64) {
-    return nullptr;
-  }
   if (!options.GetOrDefault(RuntimeArgumentMap::UseJIT)) {
     return nullptr;
   }