Convert CONFIG_RTC_DS1337 et al to Kconfig

This converts the following to Kconfig:
   CONFIG_RTC_DS1337
   CONFIG_RTC_DS1337_NOOSC
   CONFIG_RTC_DS1338
   CONFIG_RTC_DS1374
   CONFIG_RTC_DS3231
   CONFIG_RTC_MC13XXX
   CONFIG_RTC_MXS
   CONFIG_RTC_PT7C4338

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls2080aqds_nand_defconfig b/configs/ls2080aqds_nand_defconfig
index e2b6044..4fc4419 100644
--- a/configs/ls2080aqds_nand_defconfig
+++ b/configs/ls2080aqds_nand_defconfig
@@ -111,6 +111,7 @@
 CONFIG_DM_PCI_COMPAT=y
 CONFIG_PCIE_LAYERSCAPE_RC=y
 CONFIG_RTC_ENABLE_32KHZ_OUTPUT=y
+CONFIG_RTC_DS3231=y
 CONFIG_DM_SCSI=y
 CONFIG_SYS_NS16550_SERIAL=y
 CONFIG_SPI=y