boards: added CLOCK_CORECLOCK define to periph_conf

boards/arduino-due/include/periph_conf.h

@@ -27,6 +27,13 @@
 extern "C" {
 #endif
 
+/**
+ * @name Clock configuration
+ * @{
+ */
+#define CLOCK_CORECLOCK     (84000000U)
+/** @} */
+
 /**
  * @name Timer peripheral configuration
  * @{

boards/arduino-mega2560/include/periph_conf.h

@@ -23,6 +23,13 @@
 extern "C" {
 #endif
 
+/**
+ * @name        Clock configuration
+ * @{
+ */
+#define CLOCK_CORECLOCK     (16000000L)
+/** @} */
+
 /**
  * @name        Timer peripheral configuration
  * @brief       The ATmega2560 has 6 timers. Timer0 and Timer2 are 8 Bit Timers,

boards/udoo/include/periph_conf.h

@@ -25,6 +25,13 @@
 extern "C" {
 #endif
 
+/**
+ * @name Clock configuration
+ * @{
+ */
+#define CLOCK_CORECLOCK     (84000000U)
+/** @} */
+
 /**
  * @name Timer peripheral configuration
  * @{

boards/weio/include/periph_conf.h

@@ -24,6 +24,13 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Clock configuration
+ * @{
+ */
+#define CLOCK_CORECLOCK     (48000000U)
+/** @} */
+
 /**
  * @brief Timer configuration
  * @{