Revert "arm64: fix the access to tcg_op_defs[] in arm64 backend (issue #387)"

This reverts commit 3000ca6abf.

qemu/tcg/aarch64/tcg-target.c

@@ -1241,7 +1241,7 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
 {
     /* 99% of the time, we can signal the use of extension registers
        by looking to see if the opcode handles 64-bit data.  */
-    TCGType ext = (s->tcg_op_defs[opc].flags & TCG_OPF_64BIT) != 0;
+    TCGType ext = (tcg_op_defs[opc].flags & TCG_OPF_64BIT) != 0;
 
     /* Hoist the loads of the most common arguments.  */
     TCGArg a0 = args[0];