mach-stm32: stmf32f4: timer: remove clock_get() call

In order to use common clock driver between STM32F4 and
STM32F7, remove clock_get() call
As APB_PSC is always set to 2, only case when
clock_get(CLOCK_AHB) != clock_get(CLOCK_APB1) is kept

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

arch/arm/mach-stm32/stm32f4/timer.c

@@ -51,12 +51,8 @@ int timer_init(void)
 
 	setbits_le32(&STM32_RCC->apb1enr, RCC_APB1ENR_TIM2EN);
 
-	if (clock_get(CLOCK_AHB) == clock_get(CLOCK_APB1))
-		writel((clock_get(CLOCK_APB1) / CONFIG_SYS_HZ_CLOCK) - 1,
-		       &tim->psc);
-	else
-		writel(((clock_get(CLOCK_APB1) * 2) / CONFIG_SYS_HZ_CLOCK) - 1,
-		       &tim->psc);
+	writel(((CONFIG_SYS_CLK_FREQ / 2) / CONFIG_SYS_HZ_CLOCK) - 1,
+	       &tim->psc);
 
 	writel(0xFFFFFFFF, &tim->arr);
 	writel(TIM_CR1_CEN, &tim->cr1);