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/socfpga_secu1_defconfig b/configs/socfpga_secu1_defconfig
index 2c6a0a1..58e63d2 100644
--- a/configs/socfpga_secu1_defconfig
+++ b/configs/socfpga_secu1_defconfig
@@ -72,6 +72,8 @@
 CONFIG_SYS_NAND_USE_FLASH_BBT=y
 CONFIG_NAND_DENALI_DT=y
 CONFIG_SYS_NAND_ONFI_DETECTION=y
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x80000
 CONFIG_SPL_NAND_DENALI=y
 CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES=2
 # CONFIG_DM_SPI_FLASH is not set