Fix incorrect array size in gpio_free_array call

The gpio_free_array function was incorrectly passed ARRAY_SIZE(leds)
when freeing the 'buttons' array in multiple examples:
- examples/intrp.c
- examples/bottomhalf.c
- examples/bh_halfthreaded.c

This mismatch could lead to invalid memory access if the size of
'buttons' differs from 'leds'.

Updated all occurrences to use ARRAY_SIZE(buttons) for correctness.

Co-authored-by: EricccTaiwan <yphbchou0911@gmail.com>
Signed-off-by: Jordan Chiu <jordan871130@gmail.com>

Author: Jordymalone

examples/bh_threaded.c

@@ -171,7 +171,7 @@ static int __init bottomhalf_init(void)
     free_irq(button_irqs[0], &buttons[0]);
 
 fail2:
-    gpio_free_array(buttons, ARRAY_SIZE(leds));
+    gpio_free_array(buttons, ARRAY_SIZE(buttons));
 
 fail1:
     gpio_free_array(leds, ARRAY_SIZE(leds));

examples/bottomhalf.c

@@ -189,7 +189,7 @@ static int __init bottomhalf_init(void)
     free_irq(button_irqs[0], NULL);
 
 fail2:
-    gpio_free_array(buttons, ARRAY_SIZE(leds));
+    gpio_free_array(buttons, ARRAY_SIZE(buttons));
 
 fail1:
     gpio_free_array(leds, ARRAY_SIZE(leds));

examples/intrpt.c

@@ -165,7 +165,7 @@ static int __init intrpt_init(void)
     free_irq(button_irqs[0], NULL);
 
 fail2:
-    gpio_free_array(buttons, ARRAY_SIZE(leds));
+    gpio_free_array(buttons, ARRAY_SIZE(buttons));
 
 fail1:
     gpio_free_array(leds, ARRAY_SIZE(leds));