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/configs/x600_defconfig b/configs/x600_defconfig
index c8f5f66..a96f54c 100644
--- a/configs/x600_defconfig
+++ b/configs/x600_defconfig
@@ -52,6 +52,7 @@
 CONFIG_PHY_MICREL_KSZ90X1=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_MII=y
+CONFIG_RTC_M41T62=y
 CONFIG_CONS_INDEX=0
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y