riscv: ae350: Switch to use binman to generate u-boot.itb

Use the new BINMAN_STANDALONE_FDT option for AE350 based SPL defconfigs,
so that binman is now used to generate u-boot.itb.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/configs/ae350_rv64_spl_defconfig b/configs/ae350_rv64_spl_defconfig
index f434091..ef04e4a 100644
--- a/configs/ae350_rv64_spl_defconfig
+++ b/configs/ae350_rv64_spl_defconfig
@@ -3,12 +3,14 @@
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_ENV_SECT_SIZE=0x1000
 CONFIG_SPL=y
+CONFIG_DEFAULT_DEVICE_TREE="ae350_64"
 CONFIG_TARGET_AX25_AE350=y
 CONFIG_ARCH_RV64I=y
 CONFIG_RISCV_SMODE=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x00200000
+# CONFIG_USE_SPL_FIT_GENERATOR is not set
 CONFIG_BOOTDELAY=3
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SYS_PROMPT="RISC-V # "