move common code file in common directory

remove several unused files
remove mem_block_t that is never used in a different way than a simple heap buffer
move up IP address type and remove duplications of the same struct declaration

openair2/RRC/LTE/L2_interface_common.c

@@ -28,7 +28,7 @@
  * \email: raymond.knopp@eurecom.fr
  */
 
-#include "platform_types.h"
+#include "common/platform_types.h"
 #include "rrc_defs.h"
 #include "rrc_extern.h"
 #include "common/utils/LOG/log.h"