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/uniphier_v7_defconfig b/configs/uniphier_v7_defconfig
index 4ac1f94..9089be0 100644
--- a/configs/uniphier_v7_defconfig
+++ b/configs/uniphier_v7_defconfig
@@ -48,6 +48,8 @@
 CONFIG_MTD_RAW_NAND=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=0x20000
 CONFIG_SPL_NAND_DENALI=y
 CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES=8
 CONFIG_SNI_AVE=y