boards: stm32f4discovery: Refactor stm32_gs2200m.c

Summary:
- This commit refactors stm32_gs2200m.c
- gs2200m_irq_enable() and gs2200m_irq_disable() are now symmetric.

Impact:
- All use cases which use the gs2200m driver.

Testing:
- Tested with stm32f4discovery:wifi

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

boards/arm/stm32/stm32f4discovery/src/stm32_gs2200m.c

@@ -123,16 +123,7 @@ static void gs2200m_irq_enable(void)
 
   wlinfo("== ec:%d called=%d \n", _enable_count, _n_called++);
 
-  if (1 == _enable_count)
-    {
-      /* NOTE: This would happen if we received an event */
-
-      return;
-    }
-
-  _enable_count++;
-
-  if (1 == _enable_count)
+  if (0 == _enable_count)
     {
       /* Check if irq has been asserted */
 
@@ -144,6 +135,8 @@ static void gs2200m_irq_enable(void)
                          true, g_irq_handler, g_irq_arg);
     }
 
+  _enable_count++;
+
   spin_unlock_irqrestore(flags);
 
   if (dready)