bsp: gd32470z-lckfb: 增加 SPI Flash 支持及使用说明 #6430

Job	Run time
🔍 Summary of Git Diff Changes	39s
RT-Thread Online Packages (STM32F407 RT-Spark)	5m 57s
RTduino_Arduino Libraries (Raspberry Pico)	6m 31s
at32_hc32_ht32	4m 36s
others_ft32_mm32_acm32	3m 26s
stm32f0_f1	4m 51s
stm32l4	10m 0s
nxp_renesas	5m 18s
stm32_f2_f4	9m 25s
stm32_f7_g0_h7_mp15_u5_h5_wb5	6m 54s
nuvoton	3m 35s
Infineon_TI_microchip	5m 24s
gd32_n32_apm32	3m 37s
riscv-none	3m 5s
K230	1m 11s
aarch64	1m 12s
riscv64-unknown	1m 38s
mips	1m 13s
hpmicro	59s
ESP32C3	7m 21s
llvm-arm	4m 0s
i386-unknown	46s
nordic(yml)	6m 56s
simulator	1m 7s
xuantie	1m 13s
arm-none-bsp-smart	2m 20s
collect-artifacts	0s
	1h 43m 14s

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