STM32: Raise error in case of spurious interrupt

In case we've run through the entire GPIOs loop, withouth finding a
matching interrupt, we're in the case of a spurious interrupt, let's
raise an error to track it down.

Author: LMESTM

targets/TARGET_STM/gpio_irq_api.c

@@ -90,18 +90,21 @@ static void handle_interrupt_in(uint32_t irq_index, uint32_t max_num_pin_line)
             if (__HAL_GPIO_EXTI_GET_FLAG(pin) != RESET) {
                 __HAL_GPIO_EXTI_CLEAR_FLAG(pin);
 
-                if (gpio_channel->channel_ids[gpio_idx] == 0)
+                if (gpio_channel->channel_ids[gpio_idx] == 0) {
                     continue;
+                }
 
                 // Check which edge has generated the irq
                 if ((gpio->IDR & pin) == 0) {
                     irq_handler(gpio_channel->channel_ids[gpio_idx], IRQ_FALL);
                 } else {
                     irq_handler(gpio_channel->channel_ids[gpio_idx], IRQ_RISE);
                 }
+                return;
             }
         }
     }
+    error("Unexpected Spurious interrupt, index %d\r\n", irq_index);
 }