cpukit/dev/can/*: Address unused parameter warnings

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

cpukit/dev/can/can-bus.c

@@ -276,6 +276,10 @@ static int can_bus_open(
   mode_t mode
 )
 {
+  (void) path;
+  (void) oflag;
+  (void) mode;
+
   struct rtems_can_queue_ends_user_t *qends_user;
   struct rtems_can_queue_ends *qends;
   struct rtems_can_queue_edge *edge4read = NULL;

cpukit/dev/can/can-quekern.c

@@ -85,6 +85,8 @@ static inline struct rtems_can_queue_edge *can_queue_dead_edges_cut_first( void
 
 static rtems_task can_queue_dead_func( rtems_task_argument arg )
 {
+  (void) arg;
+
   struct rtems_can_queue_edge *qedge;
   struct rtems_can_queue_ends *qends;
   struct rtems_can_queue_ends *entry;

cpukit/dev/can/can-queue.c

@@ -230,6 +230,8 @@ int rtems_can_queue_abort_inslot(
   struct rtems_can_queue_slot *slot
 )
 {
+  (void) qends;
+
   int ret;
 
   ret = rtems_can_queue_fifo_abort_inslot( &qedge->fifo, slot );

cpukit/dev/can/can-virtual.c

@@ -132,6 +132,9 @@ static int virtual_chip_ioctl(
   void *arg
 )
 {
+  (void) chip;
+  (void) arg;
+
   int ret;
 
   switch( command ) {

cpukit/dev/can/ctucanfd/ctucanfd.c

@@ -1442,6 +1442,9 @@ static int ctucanfd_chip_ioctl(
   void *arg
 )
 {
+  (void) chip;
+  (void) arg;
+
   int ret;
 
   switch( command ) {