spl: move FDT_FIXUP_PARTITIONS to Kconfig

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

configs/BSC9132QDS_SDCARD_DDRCLK100_SECURE_defconfig

configs/BSC9132QDS_SDCARD_DDRCLK100_defconfig

configs/BSC9132QDS_SDCARD_DDRCLK133_SECURE_defconfig

configs/BSC9132QDS_SDCARD_DDRCLK133_defconfig

configs/BSC9132QDS_SPIFLASH_DDRCLK100_SECURE_defconfig

configs/BSC9132QDS_SPIFLASH_DDRCLK100_defconfig

configs/BSC9132QDS_SPIFLASH_DDRCLK133_SECURE_defconfig

configs/BSC9132QDS_SPIFLASH_DDRCLK133_defconfig