rtc: rx8010: don't use magic values for time buffer length

The time buffer len is used directly in this driver. For readability
it's better to define it as the difference between the date register
offsets and use sizeof() whenever referencing it.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200914154601.32245-8-brgl@bgdev.pl

drivers/rtc/rtc-rx8010.c

@@ -108,7 +108,7 @@ static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
 static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
 {
 	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
-	u8 date[7];
+	u8 date[RX8010_YEAR - RX8010_SEC + 1];
 	int flagreg, err;
 
 	flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
@@ -121,8 +121,8 @@ static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
 	}
 
 	err = i2c_smbus_read_i2c_block_data(rx8010->client, RX8010_SEC,
-					    7, date);
-	if (err != 7)
+					    sizeof(date), date);
+	if (err != sizeof(date))
 		return err < 0 ? err : -EIO;
 
 	dt->tm_sec = bcd2bin(date[RX8010_SEC - RX8010_SEC] & 0x7f);
@@ -139,7 +139,7 @@ static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
 static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
 {
 	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
-	u8 date[7];
+	u8 date[RX8010_YEAR - RX8010_SEC + 1];
 	int ctrl, flagreg, err;
 
 	if ((dt->tm_year < 100) || (dt->tm_year > 199))
@@ -164,7 +164,8 @@ static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
 	date[RX8010_WDAY - RX8010_SEC] = bin2bcd(1 << dt->tm_wday);
 
 	err = i2c_smbus_write_i2c_block_data(rx8010->client,
-					     RX8010_SEC, 7, date);
+					     RX8010_SEC, sizeof(date),
+					     date);
 	if (err < 0)
 		return err;