powerpc: t2080rdb: Enable RTC support

The T2080RDB has a ds1339 on i2c0. Add this to the devicetree and enable
the relevant support in the configs.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/configs/T2080RDB_defconfig b/configs/T2080RDB_defconfig
index d20de34..9dd01bb 100644
--- a/configs/T2080RDB_defconfig
+++ b/configs/T2080RDB_defconfig
@@ -61,6 +61,8 @@
 CONFIG_DM_PCI_COMPAT=y
 CONFIG_PCIE_FSL=y
 CONFIG_SYS_QE_FMAN_FW_IN_NOR=y
+CONFIG_DM_RTC=y
+CONFIG_RTC_DS1307=y
 CONFIG_SYS_NS16550=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y