boards/native: remove redundant ztimer configuration

Remove redundant macros since CONFIG_ZTIMER_USEC_TYPE and
CONFIG_ZTIMER_USEC_DEV were already set to their default values.

Signed-off-by: Gilles DOFFE <[email protected]>

Author: gdoffe

boards/common/native/include/board.h

@@ -143,8 +143,6 @@ void _native_LED_RED_TOGGLE(void);
  * @name    ztimer configuration
  * @{
  */
-#define CONFIG_ZTIMER_USEC_TYPE    ZTIMER_TYPE_PERIPH_TIMER
-#define CONFIG_ZTIMER_USEC_DEV     TIMER_DEV(0)
 /* on native, anything can happen... */
 #define CONFIG_ZTIMER_USEC_MIN     (64)
 /** @} */