rtc: rx8010: select REGMAP_I2C

The rtc-rx8010 uses the I2C regmap but doesn't select it in Kconfig so
depending on the configuration the build may fail. Fix it.
Signed-off-by: Yu-Tung Chang <mtwget@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210830052532.40356-1-mtwget@gmail.com

drivers/rtc/Kconfig

@@ -633,6 +633,7 @@ config RTC_DRV_FM3130
 
 config RTC_DRV_RX8010
 	tristate "Epson RX8010SJ"
+	select REGMAP_I2C
 	help
 	  If you say yes here you get support for the Epson RX8010SJ RTC
 	  chip.