Add new log category 'ms'

This is useful to track the lifecycle of MS objects. The RLCMAC cateogry
used so far in those log messages is too broad.

Change-Id: Ib4ce88d0f7309ac77c064a94bb0d667e8dbc33dd
diff --git a/src/gprs_debug.c b/src/gprs_debug.c
index 8aeca5b..ba9aeec 100644
--- a/src/gprs_debug.c
+++ b/src/gprs_debug.c
@@ -79,6 +79,13 @@
 		.loglevel = LOGL_NOTICE,
 		.enabled = 1,
 	},
+	[DMS] = {
+		.name = "DMS",
+		.color = "\033[1;34m",
+		.description = "Mobile Station (MS)",
+		.loglevel = LOGL_NOTICE,
+		.enabled = 1,
+	},
 	[DTBF] = {
 		.name = "DTBF",
 		.color = "\033[1;34m",