boards/microbit: use common clock config

boards/microbit/include/periph_conf.h

@@ -20,26 +20,12 @@
 #define PERIPH_CONF_H
 
 #include "periph_cpu.h"
+#include "cfg_clock_16_0.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/**
- * @name    Clock configuration
- *
- * @note    The radio will not work with the internal RC oscillator!
- *
- * @{
- */
-#define CLOCK_HFCLK         (16U)           /* set to  0: internal RC oscillator
-                                                      16: 16MHz crystal
-                                                      32: 32MHz crystal */
-#define CLOCK_LFCLK         (0)             /* set to  0: internal RC oscillator
-                                             *         1: 32.768 kHz crystal
-                                             *         2: derived from HFCLK */
-/** @} */
-
 /**
  * @name Timer configuration
  * @{