get toolchain info via cros_setup_toolchains

We want to centralize toolchain.conf parsing in cros_setup_toolchains.

BUG=None
TEST=`cbuildbot chromiumos-sdk` worked

Change-Id: I24c744e8bd2ededde3e4e119b6604bb3cc610729
Reviewed-on: https://gerrit.chromium.org/gerrit/24333
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
diff --git a/toolchain_utils.sh b/toolchain_utils.sh
index a4ff8d3..f4a368d 100755
--- a/toolchain_utils.sh
+++ b/toolchain_utils.sh
@@ -8,11 +8,7 @@
 
 get_all_board_toolchains()
 {
-  local board="$1"
-  local base_board=$(echo "${board}" | cut -d '_' -f 1)
-  local board_overlay=$(cros_overlay_list --board="${base_board}" \
-    --primary_only)
-  sed 's:#.*::' "${board_overlay}/toolchain.conf"
+  cros_setup_toolchains --show-board-cfg="$1" | sed 's:,: :g'
 }
 
 get_ctarget_from_board()