Fix incorrect gpio_free_array usage (#339)

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));

lkmpg.tex

@@ -1778,7 +1778,7 @@ \subsection{Spinlocks}
 In contrast, \cpp|spin_lock_irqsave()| disables interrupts and also saves the interrupt state, ensuring that interrupts are restored to their previous state when the lock is released.
 This makes \cpp|spin_lock_irqsave()| a safer option in scenarios where preserving the interrupt state is crucial.
 
-Next, \cpp|spin_lock_bh()| disables softirqs (software interrupts) but allows hardware interrupts to continue.
+Next, \cpp|spin_lock_bh()| disables \textbf{softirqs} (software interrupts) but allows hardware interrupts to continue.
 Unlike \cpp|spin_lock_irq()| and \cpp|spin_lock_irqsave()|, which disable both hardware and software interrupts, \cpp|spin_lock_bh()| is useful when hardware interrupts need to remain active.
 
 For more information about spinlock usage and lock types, see the following resources: