rsl: Add missing breaks in the code

Given that the method is only called for a traffic channels the
missing breaks didn't hurt.

Fixes: Coverity CID 1040731, CID 1040732, CID 1040733,
       CID 1040734
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index f53ba84..425dd8d 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -1718,6 +1718,7 @@
 		default:
 			break;
 		}
+		break;
 	case GSM48_CMODE_SPEECH_EFR:
 		switch (lchan->type) {
 		case GSM_LCHAN_TCH_F:
@@ -1726,6 +1727,7 @@
 		default:
 			break;
 		}
+		break;
 	case GSM48_CMODE_SPEECH_AMR:
 		switch (lchan->type) {
 		case GSM_LCHAN_TCH_F:
@@ -1735,6 +1737,7 @@
 		default:
 			break;
 		}
+		break;
 	default:
 		break;
 	}
@@ -1755,6 +1758,7 @@
 		default:
 			break;
 		}
+		break;
 	case GSM48_CMODE_SPEECH_EFR:
 		switch (lchan->type) {
 		case GSM_LCHAN_TCH_F:
@@ -1763,6 +1767,7 @@
 		default:
 			break;
 		}
+		break;
 	case GSM48_CMODE_SPEECH_AMR:
 		switch (lchan->type) {
 		case GSM_LCHAN_TCH_F:
@@ -1771,6 +1776,7 @@
 		default:
 			break;
 		}
+		break;
 	default:
 		break;
 	}