cros_run_vm_test: Pass board name to start_kvm

We need to know what kind of hardware we're virtualizing. Pass the value
of the --board flag to start_kvm so that we can configure an appropriate
virtual CPU.

BUG=chromium:484307
TEST=commit queue
CQ-DEPEND=CL:269405

Change-Id: I7fe105c7a0b1a48b54ccc64f03f237beb2cb0082
Reviewed-on: https://chromium-review.googlesource.com/269398
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Trybot-Ready: David James <davidjames@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
3 files changed