autotest: servo: Set keyboard mux before enabling keyboard control

Enabling keyboard control before setting keyboard mux causes unwanted
key presses for a short moment. Let's enable keyboard after to avoid
this.

BUG=chrome-os-partner:15547
TEST=Passed firmware_FAFTSetup.

Change-Id: I134a3ad3d2a72c906224d9db5589b582e13e3806
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/37201
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
diff --git a/server/cros/servo.py b/server/cros/servo.py
index 505f4b9..0e0c470 100644
--- a/server/cros/servo.py
+++ b/server/cros/servo.py
@@ -222,19 +222,12 @@
     def _press_and_release_keys(self, key,
                                 press_secs=SERVO_KEY_PRESS_DELAY):
         """Simulate button presses."""
-        # set keys to none
-        (m1_a1, m1_a0, m2_a1, m2_a0) = self.KEY_MATRIX[self._key_matrix]['none']
-        self.set_nocheck('kbd_m2_a0', m2_a0)
-        self.set_nocheck('kbd_m2_a1', m2_a1)
-        self.set_nocheck('kbd_m1_a0', m1_a0)
-        self.set_nocheck('kbd_m1_a1', m1_a1)
-
         (m1_a1, m1_a0, m2_a1, m2_a0) = self.KEY_MATRIX[self._key_matrix][key]
-        self.set_nocheck('kbd_en', 'on')
         self.set_nocheck('kbd_m2_a0', m2_a0)
         self.set_nocheck('kbd_m2_a1', m2_a1)
         self.set_nocheck('kbd_m1_a0', m1_a0)
         self.set_nocheck('kbd_m1_a1', m1_a1)
+        self.set_nocheck('kbd_en', 'on')
         time.sleep(press_secs)
         self.set_nocheck('kbd_en', 'off')