CONFIG_SPL_FAT_SUPPORT was removed in commit0c3a9ed409("spl: Kconfig: Replace CONFIG_SPL_FAT_SUPPORT with CONFIG_SPL_FS_FAT"). Fixup a leftover use of the symbol. Fixes:9d86dbd9cf("imx: spl: implement spl_boot_mode for i.MX7/8/8M") Signed-off-by: Harald Seiler <hws@denx.de>