bsp: qemu-virt64-riscv: remove config RISCV_S_MODE #4955

Job	Run time
RT-Thread Online Packages (STM32F407 RT-Spark)	6m 35s
RTduino/Arduino Libraries (STM32F412 Nucleo)	14m 44s
RTduino/Arduino Libraries (Raspberry Pico)	12m 17s
others_at32_hc32_ht32	7m 29s
stm32l4_f0_f1	12m 28s
stm32_f2_f4	9m 59s
stm32_f7_g0_h7_mp15_u5_h5_wb5	6m 16s
nxp_renesas	6m 50s
nuvoton	7m 44s
gd32_n32_apm32	5m 29s
Infineon_TI_microchip	6m 58s
mips	3m 37s
aarch64	7m 44s
riscv-none	3m 51s
riscv64-unknown	3m 50s
hpmicro	3m 49s
llvm-arm	5m 52s
simulator	2m 55s
ESP32C3	25m 57s
i386-unknown	5m 45s
nordic(yml)	11m 12s
	2h 51m 21s

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