Fix typos in debug message / comments

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/openbsc/src/gsm_04_11.c b/openbsc/src/gsm_04_11.c
index 4930e5c..a87c6ed 100644
--- a/openbsc/src/gsm_04_11.c
+++ b/openbsc/src/gsm_04_11.c
@@ -173,7 +173,7 @@
 		DEBUGP(DSMS, "TX: CP-ACK ");
 		break;
 	case GSM411_MT_CP_ERROR:
-		DEBUGP(DSMS, "TX: CP-ACK ");
+		DEBUGP(DSMS, "TX: CP-ERROR ");
 		break;
 	}