[fal] fix complite warning #4757

Job	Run time
RT-Thread Online Packages (STM32F407 RT-Spark)	6m 45s
RTduino/Arduino Libraries (STM32F412 Nucleo)	10m 56s
RTduino/Arduino Libraries (Raspberry Pico)	12m 24s
others_at32_hc32_ht32	6m 29s
stm32l4_f0_f1	14m 44s
stm32_f2_f4	8m 50s
stm32_f7_g0_h7_mp15_u5_h5_wb5	5m 12s
nxp_renesas	5m 42s
nuvoton	5m 17s
gd32_n32_apm32	4m 55s
Infineon_TI_microchip	6m 57s
mips	3m 33s
aarch64	4m 16s
riscv-none	2m 55s
riscv64-unknown	3m 12s
hpmicro	2m 58s
llvm-arm	6m 45s
simulator	2m 31s
ESP32C3	23m 2s
i386-unknown	2m 25s
nordic(yml)	10m 23s
	2h 30m 11s

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