arch-riscv,util: fix the default cross compiler for riscv
arch-riscv,util: fix the default cross compiler for riscv

Change-Id: I44b5f10fd9d0f3b7ac25a1adad16d5acaa44ddc3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/43607
Reviewed-by: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>
Maintainer: Gabe Black <d3e8afea784ab4a50a2dbf9149d2eaa8478e1cbc@gmail.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5