cpukit nios2: Address unused parameter warnings

Add "(void) param;" annotation to address unused parameter warnings.
Found with GCC's warning -Wunused-parameter.

cpukit/score/cpu/nios2/nios2-context-initialize.c

@@ -51,6 +51,8 @@ void _CPU_Context_Initialize(
   void *tls_area
 )
 {
+  (void) is_fp;
+
   const Nios2_MPU_Configuration *mpu_config = _Nios2_MPU_Get_configuration();
   uint32_t stack = (uint32_t) stack_area_begin + stack_area_size - 4;
 

cpukit/score/cpu/nios2/nios2-exception-frame-print.c

@@ -33,5 +33,7 @@
 
 void _CPU_Exception_frame_print( const CPU_Exception_frame *frame )
 {
+  (void) frame;
+
   /* TODO */
 }

cpukit/score/cpu/nios2/nios2-iic-irq.c

@@ -152,5 +152,7 @@ void __ISR_Handler(void)
 
 void __Exception_Handler(CPU_Exception_frame *efr)
 {
+  (void) efr;
+
   _Terminate(RTEMS_FATAL_SOURCE_EXCEPTION, 0xECC0); /* source ignored */
 }