rtc: ds1307: Clamp year to valid BCD (0-99) in set_time()

`tm_year` may go up to 299 if the device supports the
century bit. Therefore, subtracting may not give us
a valid 2-digit number, but modulo does.

Co-developed-by: Szentendrei, Tamás <[email protected]>
Signed-off-by: Szentendrei, Tamás <[email protected]>
Signed-off-by: Csókás, Bence <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

Author: Csókás, Bence

drivers/rtc/rtc-ds1307.c

@@ -359,7 +359,7 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 
 	/* assume 20YY not 19YY */
-	tmp = t->tm_year - 100;
+	tmp = t->tm_year % 100;
 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
 
 	if (chip->century_enable_bit)