rtc: mt6397: drop unused defines

RTC_NUM_YEARS has never been used, the other defines are not used since
commit 34bbdc1 ("rtc: mt6359: Add RTC hardware range and add support
for start-year")

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250303223637.1135362-1-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: alexandrebelloni

include/linux/mfd/mt6397/rtc.h

@@ -60,11 +60,6 @@
 #define RTC_PDN2               0x002e
 #define RTC_PDN2_PWRON_ALARM   BIT(4)
 
-#define RTC_MIN_YEAR           1968
-#define RTC_BASE_YEAR          1900
-#define RTC_NUM_YEARS          128
-#define RTC_MIN_YEAR_OFFSET    (RTC_MIN_YEAR - RTC_BASE_YEAR)
-
 #define MTK_RTC_POLL_DELAY_US  10
 #define MTK_RTC_POLL_TIMEOUT   (jiffies_to_usecs(HZ))