MCS: use value_string for conversion

Change-Id: I212ebb892ab162821633974d5a6c7e315d308370
diff --git a/tests/edge/EdgeTest.cpp b/tests/edge/EdgeTest.cpp
index 23abada..41a1115 100644
--- a/tests/edge/EdgeTest.cpp
+++ b/tests/edge/EdgeTest.cpp
@@ -1118,7 +1118,7 @@
 				fprintf(stderr,
 					"Encoded message block, %s, idx %d, "
 					"pattern %02x: %s\n",
-					rlc.cs.name(), block_idx, pattern,
+					mcs_name(rlc.cs), block_idx, pattern,
 					osmo_hexdump(bits, cs.sizeDL()));
 
 				Decoding::rlc_copy_to_aligned_buffer(