mgcp_find_section_end(): skip spaces at start of SDP

Change-Id: I015e0347a268b61c0ca45d40754942f87b461c09
diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index 4dd278f..670910b 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -456,15 +456,15 @@
 
 	rc = strstr(string, "\n\n");
 	if (rc)
-		return rc;
+		return rc + 2;
 
 	rc = strstr(string, "\n\r\n\r");
 	if (rc)
-		return rc;
+		return rc + 4;
 
 	rc = strstr(string, "\r\n\r\n");
 	if (rc)
-		return rc;
+		return rc + 4;
 
 	return NULL;
 }