Mips: MIPS_FS doesn't build currently, so delete it to avoid confusion.
Mips: MIPS_FS doesn't build currently, so delete it to avoid confusion.

MIPS_FS doesn't build and presumably doesn't work right now. Users might see
the MIP_FS file in build_opts and expect it to work. To avoid confusion, this
change deletes that file.

LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5