setup_board: drop unused toolchain ver flags
setup_board: drop unused toolchain ver flags

With the migration to cros_setup_toolchains, we no longer pass down the
versions of binutils/gcc/etc..., so drop the explicit flags.

BUG=chromium-os:23032
TEST=`cbuildbot x86-generic-full` works

Change-Id: I87dbb449e3c413c44cd008fc43d3258a2111227b
Reviewed-on: https://gerrit.chromium.org/gerrit/24056
Reviewed-by: Zdenek Behan <483cf2a9a4e071d4fd973db6a5a78c40f490667c@chromium.org>
Commit-Ready: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

vmware/coreos-scripts,nicescale/scripts,coreos/scripts,endocode/scripts,marineam/coreos-scripts,trnubo/scripts,BugRoger/scripts,marineam/coreos-scripts,mjg59/scripts,crawford/scripts,mjg59/scripts,glevand/coreos--scripts,crawford/scripts,smilart/scripts,vmware/coreos-scripts,andrejro/coreos--scripts,bcwaldon/coreos-scripts,zhang0137/scripts,mischief/scripts,endocode/scripts,coreos/scripts,nicescale/scripts,BugRoger/scripts,vmware/coreos-scripts,trnubo/scripts,mischief/scripts,endocode/scripts,zhang0137/scripts,glevand/coreos--scripts,nicescale/scripts,smilart/scripts,BugRoger/scripts,sigma/coreos-scripts,sigma/coreos-scripts,trnubo/scripts,mjg59/scripts,andrejro/coreos--scripts,sigma/coreos-scripts,fivethreeo/scripts,andrejro/coreos--scripts,mischief/scripts,gtank/scripts,crawford/scripts,zhang0137/scripts,bcwaldon/coreos-scripts,bcwaldon/coreos-scripts,fivethreeo/scripts,marineam/coreos-scripts,fivethreeo/scripts,smilart/scripts,gtank/scripts,gtank/scripts