rtc: always show I2C

Always show there is an I2C section, like the other sections.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -140,7 +140,6 @@ config RTC_DRV_TEST
 	  will be called rtc-test.
 
 comment "I2C RTC drivers"
-	depends on I2C
 
 if I2C