boards/esp32: DAC config approach changed

DAC pins are now configured using static arrays in header files instead of static variables in implementation to be able to define DAC_NUMOF using the size of these arrays instead of a variable.

Author: gschorcht

boards/common/esp32/include/periph_conf_common.h

@@ -73,6 +73,11 @@ extern "C" {
 #define DAC_GPIOS   { }
 #endif
 
+/**
+ * @brief   Static array with declared DAC channels
+ */
+static const gpio_t dac_channels[] = DAC_GPIOS;
+
 /**
  * @brief Number of GPIOs declared as DAC channels
  *
@@ -81,7 +86,7 @@ extern "C" {
  *
  * @note DAC_NUMOF definition must not be changed.
  */
-#define DAC_NUMOF   (dac_chn_num)
+#define DAC_NUMOF   (sizeof(dac_channels) / sizeof(dac_channels[0]))
 /** @} */