bsp/beatnik: Update due to API changes

The device_t typedef is already provided by <sys/types.h> if _KERNEL is
defined.

c/src/lib/libbsp/powerpc/beatnik/network/porting/rtemscompat.h

@@ -366,7 +366,6 @@ extern unsigned net_driver_ticks_per_sec;
 		rtems_interrupt_enable(_xtre_irq_flags); \
 	} while (0)
 
-typedef struct _netdev_t *device_t;
 typedef void (driver_intr_t)(void *);
 
 #define if_xname if_name

c/src/lib/libbsp/powerpc/beatnik/network/porting/rtemscompat1.h

@@ -12,7 +12,7 @@
  * License:   see LICENSE file.
  */
 
-typedef struct _netdev_t {
+typedef struct device {
 	struct NET_SOFTC d_softc;	/* MUST BE FIRST FIELD */
 	char			 *d_name;
 	char			 *d_desc;