boards/f4vi1: Update to match timer_init API change

boards/f4vi1/include/periph_conf.h

@@ -62,7 +62,7 @@ extern "C" {
 /* Timer 0 configuration */
 #define TIMER_0_DEV         TIM2
 #define TIMER_0_CHANNELS    4
-#define TIMER_0_PRESCALER   (83U)
+#define TIMER_0_FREQ        (CLOCK_CORECLOCK / 2)
 #define TIMER_0_MAX_VALUE   (0xffffffff)
 #define TIMER_0_CLKEN()     (RCC->APB1ENR |= RCC_APB1ENR_TIM2EN)
 #define TIMER_0_ISR         isr_tim2
@@ -71,7 +71,7 @@ extern "C" {
 /* Timer 1 configuration */
 #define TIMER_1_DEV         TIM5
 #define TIMER_1_CHANNELS    4
-#define TIMER_1_PRESCALER   (83U)
+#define TIMER_1_FREQ        (CLOCK_CORECLOCK / 2)
 #define TIMER_1_MAX_VALUE   (0xffffffff)
 #define TIMER_1_CLKEN()     (RCC->APB1ENR |= RCC_APB1ENR_TIM5EN)
 #define TIMER_1_ISR         isr_tim5