gprs_ns2: rework logging of Rx and Tx NS PDU

Introduce 2 new logging sub systems for signal and unit data.
Unify log messages so all log messages look similiar.
Log also Rx PDUs. Ensure dropped Tx packets (BLOCK/RESET on SNS)
contain *Tx*.

Change-Id: I34b8fde2955ecc010d1dcd9512e1bba9211e2c0d
diff --git a/src/logging.c b/src/logging.c
index c2a0453..4517afc 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -277,6 +277,18 @@
 		.enabled = 1, .loglevel = LOGL_NOTICE,
 		.color = "\033[38;5;59m",
 	},
+	[INT2IDX(DLNSDATA)] = {
+		.name = "DLNSDATA",
+		.description = "GPRS NS layer data PDU",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+		.color = "\033[38;5;61m",
+	},
+	[INT2IDX(DLNSSIGNAL)] = {
+		.name = "DLNSSIGNAL",
+		.description = "GPRS NS layer signal PDU",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+		.color = "\033[38;5;63m",
+	},
 };
 
 void assert_loginfo(const char *src)