examples/power: fix json null termination

coverity complains about a null-termination after a read,
so we terminate once we exit the do-while read loop.

Coverity issue: 337680
Fixes: a63504a90f ("examples/power: add JSON string handling")
Cc: stable@dpdk.org

Signed-off-by: David Hunt <david.hunt@intel.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>

examples/vm_power_manager/channel_monitor.c

@@ -822,12 +822,7 @@ read_json_packet(struct channel_info *chan_info)
 				break;
 		} while (indent > 0);
 
-		if (indent > 0)
-			/*
-			 * We've broken out of the read loop without getting
-			 * a closing brace, so throw away the data
-			 */
-			json_data[idx] = 0;
+		json_data[idx] = '\0';
 
 		if (strlen(json_data) == 0)
 			continue;