ue,stdout: fix the SNR formatting in UE console (NR)

When the SNR value is INF, the conversion to (int) causes
-2147483648 to be displayed in the UE console.
This commit fixes the formatting, so that the values INF or
NaN would be displayed as N/A

NOTE: The issue of getting an INF value for the reported SNR metric
still needs to be addressed separately.

srsue/src/metrics_stdout.cc

@@ -135,7 +135,11 @@ void metrics_stdout::set_metrics_helper(const phy_metrics_t& phy,
   fmt::print(" |");
 
   fmt::print("  {:>2}", int(phy.dl[r].mcs));
-  fmt::print("  {:>3}", int(phy.ch[r].sinr));
+  if (std::isnan(phy.ch[r].sinr) || std::isinf(phy.ch[r].sinr)) {
+    fmt::print("  {:>3}", "n/a");
+  } else {
+    fmt::print("  {:>3}", int(phy.ch[r].sinr));
+  }
   fmt::print("  {:>4.1f}", phy.dl[r].fec_iters);
 
   fmt::print(" {:>6.6}", float_to_eng_string((float)mac[r].rx_brate / (mac[r].nof_tti * 1e-3), 2));