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/ls1046aqds_nand_defconfig b/configs/ls1046aqds_nand_defconfig
index c325ee3..8168b6e 100644
--- a/configs/ls1046aqds_nand_defconfig
+++ b/configs/ls1046aqds_nand_defconfig
@@ -73,6 +73,8 @@
 CONFIG_SYS_FLASH_CFI=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_SF_DEFAULT_BUS=1
 CONFIG_PHYLIB=y
 CONFIG_PHYLIB_10G=y