* nios2-mpu-configuration.c, nios2-mpu-descriptor.c,
nios2-mpu-disable-protected.c, nios2-mpu-reset.c: New files.
* Makefile.am: Reflect changes above.
* rtems/score/nios2-utility.h, nios2-context-initialize.c: Added
support for the memory protection unit (MPU).