Avoid unnecessary empty lines when instruction tracing is on

These empty lines don't add to the readability of the trace and in fact
when trace redirection is enabled they result in lots of empty lines being
printed to stderr which makes it impossible to read the OS boot messages.

c_emulator/riscv_sim.c

@@ -740,9 +740,7 @@ int compare_states(struct tv_spike_t *s)
 void flush_logs(void)
 {
   if (config_print_instr) {
-    fprintf(stderr, "\n");
     fflush(stderr);
-    fprintf(trace_log, "\n");
     fflush(trace_log);
   }
 }