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/imx6ul_geam_nand_defconfig b/configs/imx6ul_geam_nand_defconfig
index 9012177..f186097 100644
--- a/configs/imx6ul_geam_nand_defconfig
+++ b/configs/imx6ul_geam_nand_defconfig
@@ -53,6 +53,8 @@
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_MXS=y
 CONFIG_SYS_NAND_ONFI_DETECTION=y
+CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
+CONFIG_SYS_NAND_U_BOOT_OFFS=0x200000
 CONFIG_PHYLIB=y
 CONFIG_PHY_SMSC=y
 CONFIG_FEC_MXC=y