mgw: Support receiving lowercase LCO codec

MGCP RFC3435 (https://tools.ietf.org/html/rfc3435) states almost all
text has to be handled in a case-insensitive way, except SDP parts.

Related: OS#4001
Change-Id: I51dc1cdcbe2a5587769335fbecb5039ef22cae5d
diff --git a/tests/mgcp/mgcp_test.c b/tests/mgcp/mgcp_test.c
index 5a14bdf..39fe5d0 100644
--- a/tests/mgcp/mgcp_test.c
+++ b/tests/mgcp/mgcp_test.c
@@ -214,7 +214,7 @@
 	"m: sendrecv\r" \
 	"c: 2\r\n" \
 	"i: %s\r\n" \
-	"l: A:AMR, NT:IN\r\n" \
+	"l: A:amr, NT:IN\r\n" \
 	"\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 0.0.0.0\r\n" \