bsps/mips/jmr3904: Address unused parameter warnings

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

bsps/mips/jmr3904/console/console-io.c

@@ -99,6 +99,8 @@ void console_outbyte_polled(
   char ch
 )
 {
+  (void) port;
+
   unsigned short disr;
 
   for (;;) {
@@ -121,6 +123,8 @@ int console_inbyte_nonblocking(
   int port
 )
 {
+  (void) port;
+
   unsigned char c;
   unsigned short disr;
 

bsps/mips/jmr3904/irq/vectorisrs.c

@@ -41,6 +41,8 @@
 
 void mips_vector_isr_handlers( CPU_Interrupt_frame *frame )
 {
+  (void) frame;
+
   unsigned int sr;
   unsigned int cause;
 

bsps/mips/jmr3904/start/bspstart.c

@@ -73,6 +73,8 @@ void bsp_start( void )
  */
 void clear_cache( void *address, size_t n )
 {
+  (void) address;
+  (void) n;
 }