s cpu: moved pwm_conf_[chan_]t to periph_cpu.h

cpu/samd21/include/periph_cpu.h

@@ -79,6 +79,23 @@ typedef enum {
     GPIO_MUX_H = 0x7,       /**< select peripheral function H */
 } gpio_mux_t;
 
+/**
+ * @brief   PWM channel configuration data structure
+ */
+typedef struct {
+    gpio_t pin;                 /**< GPIO pin */
+    gpio_mux_t mux;             /**< pin function multiplex value */
+    uint8_t chan;               /**< TCC channel to use */
+} pwm_conf_chan_t;
+
+/**
+ * @brief   PWM device configuration data structure
+ */
+typedef struct {
+    Tcc *dev;                   /*< TCC device to use */
+    pwm_conf_chan_t chan[2];    /**< channel configuration */
+} pwm_conf_t;
+
 /**
  * @brief   UART device configuration
  */