Convert CONFIG_SYS_NAND_U_BOOT_LOCATIONS et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_NAND_U_BOOT_LOCATIONS
   CONFIG_SYS_NAND_U_BOOT_OFFS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls1043ardb_nand_defconfig b/configs/ls1043ardb_nand_defconfig
index a03e3d0..c778c78 100644
--- a/configs/ls1043ardb_nand_defconfig
+++ b/configs/ls1043ardb_nand_defconfig
@@ -72,6 +72,8 @@
 CONFIG_NAND_FSL_IFC=y
 CONFIG_SYS_NAND_BLOCK_SIZE=0x20000
 CONFIG_SYS_NAND_ONFI_DETECTION=y
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x20000
 CONFIG_SF_DEFAULT_BUS=1
 CONFIG_PHYLIB=y
 CONFIG_PHY_AQUANTIA=y