Move RTEMS-specific Termios API content

Remove obsolete support for OFILL, OFDEL, NLDLY, CRDLY, BSDLY, VTDLY,
and FFDLY which is not present on FreeBSD and not implemented in Linux.

Update #2833.

c/src/libchip/serial/mc68681.h

@@ -11,6 +11,8 @@
 #ifndef _MC68681_H_
 #define _MC68681_H_
 
+#include <rtems/termiostypes.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif