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/src/libosmo-mgcp/mgcp_endp.c b/src/libosmo-mgcp/mgcp_endp.c
index f0ad0a7..668d88b 100644
--- a/src/libosmo-mgcp/mgcp_endp.c
+++ b/src/libosmo-mgcp/mgcp_endp.c
@@ -21,7 +21,9 @@
  *
  */
 
-#include <osmocom/mgcp/mgcp_internal.h>
+#include <osmocom/mgcp/mgcp.h>
+#include <osmocom/mgcp/mgcp_protocol.h>
+#include <osmocom/mgcp/mgcp_conn.h>
 #include <osmocom/mgcp/mgcp_endp.h>
 #include <osmocom/mgcp/mgcp_trunk.h>