Kconfig: Migrate CONFIG_RTC_M41T62 define to Kconfig

This patch moves the RTC M41T62 config define to Kconfig.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6038b43..fd0009b 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -104,4 +104,10 @@
 	  clock with a wide array of features and 50 bytes of general-purpose,
 	  battery-backed RAM. The driver supports access to the clock and RAM.
 
+config RTC_M41T62
+	bool "Enable M41T62 driver"
+	help
+	  Enable driver for ST's M41T62 compatible RTC devices (like RV-4162).
+	  It is a serial (I2C) real-time clock (RTC) with alarm.
+
 endmenu