The RTC_VL_READ ioctl reports the low battery condition. Still,
pcf8523_rtc_read_time() happily returns invalid dates in this case.
Check the battery health on pcf8523_rtc_read_time() to avoid that.
Reported-by: Erik Čuk <erik.cuk@domel.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>