tcg: Drop plugin_gen_disable_mem_helpers from tcg_gen_exit_tb

Now that we call qemu_plugin_disable_mem_helpers in cpu_tb_exec,
we don't need to do this in generated code as well.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230310195252.210956-3-richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230315174331.2959-13-alex.bennee@linaro.org>
Reviewed-by: Emilio Cota <cota@braap.org>

tcg/tcg-op.c

@@ -2808,7 +2808,6 @@ void tcg_gen_exit_tb(const TranslationBlock *tb, unsigned idx)
         tcg_debug_assert(idx == TB_EXIT_REQUESTED);
     }
 
-    plugin_gen_disable_mem_helpers();
     tcg_gen_op1i(INDEX_op_exit_tb, val);
 }