Move CONFIG_OF_LIBFDT to Kconfig

configs/B4420QDS_NAND_defconfig

configs/B4420QDS_SPIFLASH_defconfig

configs/B4420QDS_defconfig

configs/B4860QDS_NAND_defconfig

configs/B4860QDS_SECURE_BOOT_defconfig

configs/B4860QDS_SPIFLASH_defconfig

configs/B4860QDS_SRIO_PCIE_BOOT_defconfig

configs/B4860QDS_defconfig

configs/BSC9131RDB_NAND_SYSCLK100_defconfig

configs/BSC9131RDB_NAND_defconfig

configs/BSC9131RDB_SPIFLASH_SYSCLK100_defconfig

configs/BSC9131RDB_SPIFLASH_defconfig

configs/BSC9132QDS_NAND_DDRCLK100_SECURE_defconfig

configs/BSC9132QDS_NAND_DDRCLK100_defconfig

configs/BSC9132QDS_NAND_DDRCLK133_SECURE_defconfig

configs/BSC9132QDS_NAND_DDRCLK133_defconfig

configs/BSC9132QDS_NOR_DDRCLK100_SECURE_defconfig

configs/BSC9132QDS_NOR_DDRCLK100_defconfig

configs/BSC9132QDS_NOR_DDRCLK133_SECURE_defconfig

configs/BSC9132QDS_NOR_DDRCLK133_defconfig