fix gcc 4.2.1 warning: discards qualifiers from pointer target type

src/drivers/net/via-velocity.c

  */
 
 static void velocity_set_int_opt(int *opt, int val, int min, int max,
-				 int def, char *name, char *devname)
+				 int def, char *name, const char *devname)
 {
 	if (val == -1) {
 		printf("%s: set value of parameter %s to %d\n",
  */
 
 static void velocity_set_bool_opt(u32 * opt, int val, int def, u32 flag,
-				  char *name, char *devname)
+				  char *name, const char *devname)
 {
 	(*opt) &= (~flag);
 	if (val == -1) {
  */
 
 static void velocity_get_options(struct velocity_opt *opts, int index,
-				 char *devname)
+				 const char *devname)
 {
 
 	/* FIXME Do the options need to be configurable */
 	DBG ( "%s: %s at ioaddr %#hX\n", pci->driver_name, eth_ntoa ( nic->node_addr ),
 	      (unsigned int) BASE );
 
-	velocity_get_options(&vptr->options, 0, (char *) pci->driver_name);
+	velocity_get_options(&vptr->options, 0, pci->driver_name);
 
 	/* 
 	 *      Mask out the options cannot be set to the chip