Fix syscall gettimeofday in 32-bit emulator

[qwe661234]

When running the 32-bit emulator, we've discovered that the proxy kernel generates inaccurate time results when the 'gettimeofday' system call is made. However, the 64-bit emulator doesn't seem to be impacted by this issue. To address this problem, we've made a modification to the system by forwarding the 'gettimeofday' system call to the Spike front-end server. This allows us to receive the correct time results and resolve the problem. The modification includes both the proxy kernel and Spike.

Issue reproduction

• dhrystone source code

  1. Compile

  riscv32-unknown-elf-gcc -march=rv32g -O2 ./dhrystone.c -o dhrystone.elf

  2. Execute

  /path/to/spike --isa=rv32g /path/to/32-bit_proxy_kernel dhrystone.elf

  Related: https://github.com/riscv-software-src/riscv-isa-sim/pull/1318