rtc: cmos: unregister HPET IRQ handler on probe failure

rtc: cmos: unregister HPET IRQ handler on probe failure

cmos_do_probe() registers cmos_interrupt() as the HPET RTC IRQ
handler before requesting the RTC IRQ and registering the RTC
device. If either request_irq() or devm_rtc_register_device()
fails afterwards, the error path leaves the HPET RTC IRQ handler
installed. This leaves a stale handler behind and make a later
hpet_register_irq_handler() fail with -EBUSY.

Track whether the HPET handler was registered successfully and
undo the registration on the probe error path. Also mask the HPET
RTC IRQ bits to match the normal shutdown cleanup.

Fixes: 9d8af78b0797 ("rtc: add HPET RTC emulation to RTC_DRV_CMOS")
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Link: https://patch.msgid.link/20260623100848.2127281-1-haoxiang_li2024@163.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>