bisect-kit: support reboot DUTs in the lab via servo

This works around the issue that DUTs sometimes become unresponsive
during reboot.

BUG=b:166742293
TEST=./cros_helper.py reboot $DUT

Change-Id: I484fabb2105646f5a114323d8abf1f62f5b8fd6a
diff --git a/eval_cros_autotest.py b/eval_cros_autotest.py
index 01fa50d..c540df3 100755
--- a/eval_cros_autotest.py
+++ b/eval_cros_autotest.py
@@ -22,6 +22,7 @@
 from bisect_kit import cli
 from bisect_kit import common
 from bisect_kit import configure
+from bisect_kit import cros_lab_util
 from bisect_kit import cros_util
 from bisect_kit import util
 
@@ -180,7 +181,8 @@
     util.ssh_cmd(opts.dut, 'rm', '-rf', '/usr/local/autotest')
 
   if opts.reboot_before_test:
-    cros_util.reboot(opts.dut)
+    cros_util.reboot(
+        opts.dut, force_reboot_callback=cros_lab_util.reboot_via_servo)
 
 
 def run_test(opts):