Cleanup toolchain source code download script

qemu is a submodule but is never built in the flow. Avoid initializing
the submodule to prevent breakage building for CentOS7

Change-Id: I5e1a8e248fc38bbcac1674cb5db84c918a0f3417

download-toolchain.sh

diff --git a/download-toolchain.sh b/download-toolchain.sh
index 2204c54..e30eb04 100755
--- a/download-toolchain.sh
+++ b/download-toolchain.sh
@@ -35,9 +35,6 @@
 TOOLCHAINLLVM_TAG="2021.06.18"
 TOOLCHAINLLVM_BINUTILS_URL="git://sourceware.org/git/binutils-gdb.git"
 
-
-TOOLCHAIN_OUT="${CACHE}/toolchain"
-
 if [[ ! "${TOOLCHAIN_TARGET}" == "GCC" ]] &&
   [[ ! "${TOOLCHAIN_TARGET}" == "LLVM" ]]; then
   echo "Unsupported toochain target: ${TOOLCHAIN_TARGET}"
@@ -66,7 +63,7 @@
 # Update the submodules. The riscv-binutils has to point to upstream binutil-gdb
 # regardless of what it is in .gitmodules
 pushd "${TOOLCHAIN_GCC_SRC}" > /dev/null
-git submodule update --init --jobs=8
+git submodule update --init --jobs=8 riscv-*
 if [[ "${TOOLCHAIN_TARGET}" == "LLVM" ]]; then
   cd "riscv-binutils"
   git remote set-url origin "${TOOLCHAINLLVM_BINUTILS_URL}"