rtc: m41t80: kickstart ocillator upon failure

rtc: m41t80: kickstart ocillator upon failure

The ocillator on the m41t62 (and other chips of this type) needs
a kickstart upon a failure; the RTC read routine will notice the
oscillator failure and fail reads.  This is added in the RTC write
routine; this allows the system to know that the time in the RTC
is accurate.  This is following the procedure described in section
3.11 of  "https://www.st.com/resource/en/datasheet/m41t62.pdf"

Signed-off-by: A. Niyas Ahamed Mydeen <nmydeen@mvista.com>
Reviewed-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/20250402120546.336657-2-nmydeen@mvista.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>