Convert CONFIG_SYS_NAND_U_BOOT_OFFS to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_NAND_U_BOOT_OFFS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/T2080RDB_revD_NAND_defconfig b/configs/T2080RDB_revD_NAND_defconfig
index e03d3888..cdd7524 100644
--- a/configs/T2080RDB_revD_NAND_defconfig
+++ b/configs/T2080RDB_revD_NAND_defconfig
@@ -87,6 +87,8 @@
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_FSL_IFC=y
 CONFIG_SYS_NAND_ONFI_DETECTION=y
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x40000
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SF_DEFAULT_SPEED=10000000
 CONFIG_SPI_FLASH_STMICRO=y