mgw: Support lowercase header parameters

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: I48252415f9d0cd985ad097f334aa4c1665f52511
diff --git a/tests/mgcp/mgcp_test.c b/tests/mgcp/mgcp_test.c
index ab6d0ce..c67b9d5 100644
--- a/tests/mgcp/mgcp_test.c
+++ b/tests/mgcp/mgcp_test.c
@@ -211,10 +211,10 @@
 /* Test different upper/lower case in options */
 #define MDCX4_PT4 \
 	"MDCX 18983220 1@mgw MGCP 1.0\r\n" \
-	"M: sendrecv\r" \
-	"C: 2\r\n" \
-	"I: %s\r\n" \
-	"L: A:AMR, NT:IN\r\n" \
+	"m: sendrecv\r" \
+	"c: 2\r\n" \
+	"i: %s\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" \
@@ -260,7 +260,7 @@
 
 #define CRCX \
 	"CRCX 2 1@mgw MGCP 1.0\r\n" \
-	"M: recvonly\r\n" \
+	"m: recvonly\r\n" \
 	"C: 2\r\n" \
 	"L: p:20\r\n" \
 	"\r\n" \