fix nxstyle errors and warnings

Signed-off-by: Michal Lenc <michallenc@seznam.cz>

arch/arm/src/imxrt/imxrt_tickless.c

@@ -204,7 +204,6 @@ static void imxrt_interval_handler(void)
 static void imxrt_timing_handler(void)
 {
   g_tickless.overflow++;
-  uint32_t regval;
 
   /* Clear interrupt bit */
 
@@ -219,10 +218,11 @@ static void imxrt_timing_handler(void)
  *   interrupt and fires the appropriate handler.
  *
  * Input Parameters:
- *   None
+ *   irq     - Number of the IRQ that generated the interrupt
+ *   context - Interrupt register state save info (architecture-specific)
  *
  * Returned Value:
- *   None
+ *   OK on success
  *
  ****************************************************************************/