[autotest] Add mistral to jetstream boards.

BUG=None
TEST=unit tests

Change-Id: I2aa38a55f4f4922c895da9e59b4334149746921b
Reviewed-on: https://chromium-review.googlesource.com/1450794
Commit-Ready: Laurence Goodby <lgoodby@chromium.org>
Tested-by: Laurence Goodby <lgoodby@chromium.org>
Reviewed-by: Kan Yan <kyan@chromium.org>
Reviewed-by: Alex Zamorzaev <zamorzaev@chromium.org>
diff --git a/server/hosts/servo_repair.py b/server/hosts/servo_repair.py
index 21730dc..c90fbbc 100644
--- a/server/hosts/servo_repair.py
+++ b/server/hosts/servo_repair.py
@@ -221,7 +221,7 @@
     """
     # TODO (crbug.com/646593) - Remove list below once servo has been updated
     # with a dummy pwr_button signal.
-    _BOARDS_WO_PWR_BUTTON = ['arkham', 'storm', 'whirlwind', 'gale']
+    _BOARDS_WO_PWR_BUTTON = ['arkham', 'gale', 'mistral', 'storm', 'whirlwind']
 
     def verify(self, host):
         if host.servo_board in self._BOARDS_WO_PWR_BUTTON: