net: lwm2m: Trace clean

Cleaned Trace message print.

Signed-off-by: Juha Heiskanen <juha.heiskanen@nordicsemi.no>
diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.c b/subsys/net/lib/lwm2m/lwm2m_engine.c
index 00ea4f9..8f54b31 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.c
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.c
@@ -126,9 +126,7 @@
 		return net_addr_ntop(AF_INET, &net_sin(addr)->sin_addr, buf, sizeof(buf));
 	}
 
-	LOG_ERR("Unknown IP address family:%d", addr->sa_family);
-	strcpy(buf, "unk");
-	return buf;
+	return "::";
 }
 
 static uint8_t to_hex_digit(uint8_t digit)
diff --git a/subsys/net/lib/lwm2m/lwm2m_message_handling.c b/subsys/net/lib/lwm2m/lwm2m_message_handling.c
index 877ee75..c84ceae 100644
--- a/subsys/net/lib/lwm2m/lwm2m_message_handling.c
+++ b/subsys/net/lib/lwm2m/lwm2m_message_handling.c
@@ -2292,7 +2292,6 @@
 		}
 	}
 
-	LOG_DBG("checking for reply from [%s]", lwm2m_sprint_ip_addr(from_addr));
 	reply = coap_response_received(&response, from_addr, client_ctx->replies,
 				       ARRAY_SIZE(client_ctx->replies));
 	if (reply) {