get rid of mgcp_internal.h

The file mgcp_internal.h still contains mostly definitions and types
that are relevant for mgcp_network.c and mgcp_protocol.c. Lets give
the network and protocol module its own header files, also move stuff
that does not relate to protocol and network to the appropiate places.

Change-Id: I837eaad771ed7252304db4a81c37953b70766fff
diff --git a/include/osmocom/mgcp/mgcp_codec.h b/include/osmocom/mgcp/mgcp_codec.h
index caeecb0..97650e4 100644
--- a/include/osmocom/mgcp/mgcp_codec.h
+++ b/include/osmocom/mgcp/mgcp_codec.h
@@ -1,5 +1,15 @@
 #pragma once
 
+#define DEFAULT_RTP_AUDIO_FRAME_DUR_NUM 20
+#define DEFAULT_RTP_AUDIO_FRAME_DUR_DEN 1000
+#define DEFAULT_RTP_AUDIO_PACKET_DURATION_MS 20
+#define DEFAULT_RTP_AUDIO_DEFAULT_RATE  8000
+#define DEFAULT_RTP_AUDIO_DEFAULT_CHANNELS 1
+
+#define PTYPE_UNDEFINED (-1)
+
+struct mgcp_conn_rtp;
+
 void mgcp_codec_summary(struct mgcp_conn_rtp *conn);
 void mgcp_codec_reset_all(struct mgcp_conn_rtp *conn);
 int mgcp_codec_add(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const struct mgcp_codec_param *param);