ARM64: Fix native cctest

CPUFeatures::Probe has been modified such that it can be called only once, but
the cctests make two calls in native builds: once in VM init, and once in each
test setup. This patch removes the call in the test setup.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/285273003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21337 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/test-assembler-arm64.cc

@@ -173,8 +173,7 @@ static void InitializeVM() {
   ASSERT(isolate != NULL);                                                     \
   byte* buf = new byte[buf_size];                                              \
   MacroAssembler masm(isolate, buf, buf_size);                                 \
-  RegisterDump core;                                                           \
-  CpuFeatures::Probe(false);
+  RegisterDump core;
 
 #define RESET()                                                                \
   __ Reset();                                                                  \