Use power_short_press to boot the DUT instead of power_normal_press.

The power_normal_press delays 1.2 seconds. A fast machine boots to the
firmware screen in 1.2 seconds and it checks that the power button is pressed.
As a result, the machine is then shutdown. So we now change to use
power_short_press which is 0.1 second.

BUG=chromium-os:24754
TEST=run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
        servo_vid=0x18d1 servo_pid=0x5001" firmware_FwScreenPressPower

Change-Id: I60759d04e9453ebb04173f5933f383e03a6c9dca
Reviewed-on: https://gerrit.chromium.org/gerrit/14049
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
diff --git a/server/cros/faftsequence.py b/server/cros/faftsequence.py
index 8ec78d3..5c0a5c0 100644
--- a/server/cros/faftsequence.py
+++ b/server/cros/faftsequence.py
@@ -489,7 +489,7 @@
     def wait_fw_screen_and_press_power(self):
         """Wait for firmware warning screen and press power button."""
         time.sleep(self.FIRMWARE_SCREEN_DELAY)
-        self.servo.power_normal_press()
+        self.servo.power_short_press()
 
 
     def wait_fw_screen_and_close_lid(self):
@@ -735,7 +735,7 @@
 
         if pre_power_action:
             self._call_action(pre_power_action)
-        self.servo.power_normal_press()
+        self.servo.power_short_press()
         if post_power_action:
             self._call_action(post_power_action)