u-boot cannot recognize FIT image built from kernel

[sprhawk]

I'm using Yocto (dunfell) to build Embeded Linux on arm64,
u-boot: 2020-10rc5,
linux-yocto: 5.4

the generated FIT image can be displayed by mkimage -l :

> FIT description: U-Boot fitImage for Poky (Yocto Project Reference
> Distro)/5.4.61+gitAUTOINC+416566e1f0_00809fdaf6/backupstack-rk3368
> Created:         Wed Aug 26 16:04:39 2020
>  Image 0 (kernel at 1)
>   Description:  Linux kernel
>   Created:      Wed Aug 26 16:04:39 2020
>   Type:         Kernel Image
>   Compression:  gzip compressed
>   Data Size:    7513871 Bytes = 7337.76 KiB = 7.17 MiB
>   Architecture: AArch64
>   OS:           Linux
>   Load Address: 0x06000000
>   Entry Point:  0x06000000
>   Hash algo:    sha256
>   Hash value:
> d31c9a001e6268ef0f02ca0dfe11ac0693696d64ca926ff3f110a1567da259e6
>  Image 1 (fdt at rockchip_rk3368-lion-haikou.dtb)
>   Description:  Flattened Device Tree blob
>   Created:      Wed Aug 26 16:04:39 2020
>   Type:         Flat Device Tree
>   Compression:  uncompressed
>   Data Size:    26828 Bytes = 26.20 KiB = 0.03 MiB
>   Architecture: AArch64
>   Hash algo:    sha256
>   Hash value:
> 6a5c3a396ef786d929894673679316ab027bff4af5fec95ad7a1fae46be6fe8e
>  Default Configuration: 'conf at rockchip_rk3368-lion-haikou.dtb'
>  Configuration 0 (conf at rockchip_rk3368-lion-haikou.dtb)
>   Description:  1 Linux kernel, FDT blob
>   Kernel:       kernel at 1
>   FDT:          fdt at rockchip_rk3368-lion-haikou.dtb
>   Hash algo:    sha256
>   Hash value:   unavailable
>

But inside u-boot, it cannot boot FIT image, reports debug info cannot find
`description` property.

I use fdt command under u-boot, found:

> => fdt addr $kernel_addr_r
> => fdt list
> / {
>         <NULL> = <0x5f468817>;
>         <NULL> = "U-Boot fitImage for Poky (Yocto Project Reference
> Distro)/5.4.61+gitAUTOINC+416566e1f0_00809fdaf6/backupstack-rk3368";
>         <NULL> = <0x00000001>;
>         images {
> =>
>

I guess somewhat u-boot cannot correctly recognize FIT image format?