drivers: timer: Fix conversion issue in stm32 lptim timer

Using correct macro to convert stdby time in LPTIM counter

Signed-off-by: Alessandro Manganaro <[email protected]>

Author: asm5878

drivers/timer/stm32_lptim_timer.c

@@ -627,7 +627,7 @@ void sys_clock_idle_exit(void)
 		stdby_timer_us = counter_ticks_to_us(stdby_timer, stdby_timer_diff);
 
 		/* Convert standby time in LPTIM cnt */
-		missed_lptim_cnt = (sys_clock_hw_cycles_per_sec() * stdby_timer_us) /
+		missed_lptim_cnt = (CONFIG_STM32_LPTIM_CLOCK * stdby_timer_us) /
 				   USEC_PER_SEC;
 		/* Add the LPTIM cnt pre standby */
 		missed_lptim_cnt += lptim_cnt_pre_stdby;