rtc: add data_race() in rtc_dev_poll()

rtc: add data_race() in rtc_dev_poll()

The unlocked read of rtc->irq_data in rtc_dev_poll() can race with
the write in rtc_handle_legacy_irq() and also, theoretically, with
the write in rtc_dev_read().

These races should be safe (see inline comment), thus annotate the
read with data_race() for KCSAN.

Reported-by: syzbot+2d4127acca35ed7b31ad@syzkaller.appspotmail.com
Closes: https://syzbot.org/bug?extid=2d4127acca35ed7b31ad
Signed-off-by: Mauricio Faria de Oliveira <mfo@igalia.com>
Link: https://patch.msgid.link/20260317-irq_data-v1-1-a2741002be60@igalia.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>