Vector extension test (vfdiv, vfmax, vfmin, vfmul)

1. Define additional operations (vfdiv, vfmax, vfmin, vfmul)
2. Fix typos in softrvv/include/softrvv_vfsub.h
3. Remove unnecessary header files in softrvv/include/softrvv_vmax.h and softrvv/include/softrvv_vmin.h
4. Add tests for newly added operations in tests/CMakeLists.txt
- They are tested with "m springbok && ctest --verbose -R ... --gtest_color=yes"

Change-Id: Ia84de66974f0e41b0373e112d19393a7d4ca5b0a
9 files changed