ex400: uboot: add FIT support

Signed-off-by: Bartlomiej Grzeskowiak <bartlomiej.grzeskowiak@iopsys.eu>

configs/ex400_defconfig

@@ -79,11 +79,15 @@ CONFIG_SYS_MALLOC_CLEAR_ON_INIT=y
 #
 # Boot images
 #
-# CONFIG_FIT is not set
+CONFIG_FIT=y
+# CONFIG_FIT_VERBOSE is not set
+# CONFIG_FIT_SIGNATURE is not set
+# CONFIG_FIT_BEST_MATCH is not set
 # CONFIG_OF_BOARD_SETUP is not set
 # CONFIG_OF_SYSTEM_SETUP is not set
 # CONFIG_OF_STDOUT_VIA_ALIAS is not set
 CONFIG_SYS_EXTRA_OPTIONS=""
+# CONFIG_SPL_LOAD_FIT is not set
 CONFIG_ARCH_FIXUP_FDT=y
 
 #