Input: gpio-keys - fix crash when disabliing GPIO-less buttons

Input: gpio-keys - fix crash when disabliing GPIO-less buttons

My brain-damaged adjustments to Paul's patch caused crashes in
gpio_keys_disable_button() when driver is used in GPIO-less (i.e.
purely interrupt-driven) setups, because I mixed together debounce and
release timers when they are in fact separate:

Unable to handle kernel NULL pointer dereference at virtual address 0000000c
...
PC is at hrtimer_active+0xc/0x98
LR is at hrtimer_try_to_cancel+0x24/0x140
...
[<c01c43b8>] (hrtimer_active) from [<c01c50f4>] (hrtimer_try_to_cancel+0x24/0x140)
[<c01c50f4>] (hrtimer_try_to_cancel) from [<c01c5224>] (hrtimer_cancel+0x14/0x4c)
[<c01c5224>] (hrtimer_cancel) from [<bf1cae24>] (gpio_keys_attr_store_helper+0x1b8/0x1d8 [gpio_keys])
[<bf1cae24>] (gpio_keys_attr_store_helper [gpio_keys]) from [<bf1cae80>] (gpio_keys_store_disabled_keys+0x18/0x24 [gpio_keys])
[<bf1cae80>] (gpio_keys_store_disabled_keys [gpio_keys]) from [<c038ec7c>] (kernfs_fop_write_iter+0x10c/0x1cc)
[<c038ec7c>] (kernfs_fop_write_iter) from [<c02df858>] (vfs_write+0x2ac/0x404)
[<c02df858>] (vfs_write) from [<c02dfaf4>] (ksys_write+0x64/0xdc)
[<c02dfaf4>] (ksys_write) from [<c0100080>] (ret_fast_syscall+0x0/0x58)

Let's fix it up.

Fixes: c9efb0ba281e ("Input: gpio-keys - use hrtimer for software debounce, if possible")
Reported-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/YG1DFFgojSVfdpaz@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>