faft: Speed up the waiting time for dev screen and sync

Waiting for a dev screen and pressing Ctrl-D is a recurrent action.
Booting to a dev screen is a bit faster than other firmware screens,
like recovery insert screen. We can make the dev screen a separated
case from other firmware screens for speed-up. It can save 3 seconds
each time.

Also the sync delay can be faster, from 5 seconds to 2 seconds.

BUG=chromium-os:34392
TEST=run FAFT suite on Link and the dev screen timing is correct.

Change-Id: I377494cc44b4bb9ca3e2d2addee3cb34a2d511d0
Reviewed-on: https://gerrit.chromium.org/gerrit/38630
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
diff --git a/server/cros/faft_delay_constants.py b/server/cros/faft_delay_constants.py
index 1675aff..c4c34c3 100644
--- a/server/cros/faft_delay_constants.py
+++ b/server/cros/faft_delay_constants.py
@@ -8,6 +8,8 @@
 
     # Delay between power-on and firmware screen
     firmware_screen = 10
+    # Delay between power-on and dev screen
+    dev_screen = 7
     # Delay between keypresses in firmware screen
     confirm_screen = 3
     # Delay between passing firmware screen and text mode warning screen
@@ -21,7 +23,7 @@
     # Delay between USB plug-out and plug-in
     between_usb_plug = 10
     # Delay after running the 'sync' command
-    sync = 5
+    sync = 2
     # Delay for waiting client to shutdown
     shutdown = 30
     # Delay for waiting client to return before sending EC reboot command
@@ -59,3 +61,4 @@
 
         if platform == 'Link':
             self.firmware_screen = 7
+            self.dev_screen = 4