Input: gpio-keys - fix possible concurrent access in gpio_keys_irq_timer()

Input: gpio-keys - fix possible concurrent access in gpio_keys_irq_timer()

gpio_keys_irq_isr() and gpio_keys_irq_timer() access the same resources.
There could be a concurrent access if a GPIO interrupt occurs in parallel
of a HR timer interrupt.

Guard back those resources with a spinlock.

Fixes: 019002f20cb5 ("Input: gpio-keys - use hrtimer for release timer")
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Link: https://lore.kernel.org/r/20250528-gpio_keys_preempt_rt-v2-2-3fc55a9c3619@foss.st.com
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>