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/P1020RDB-PD_NAND_defconfig b/configs/P1020RDB-PD_NAND_defconfig
index 130dea9..874b338 100644
--- a/configs/P1020RDB-PD_NAND_defconfig
+++ b/configs/P1020RDB-PD_NAND_defconfig
@@ -88,6 +88,8 @@
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_FSL_ELBC=y
 CONFIG_SYS_NAND_BLOCK_SIZE=0x20000
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x20000
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SF_DEFAULT_SPEED=10000000
 CONFIG_SPI_FLASH_SPANSION=y