ryu: Disable USB D+ pull-up on boot
ryu: Disable USB D+ pull-up on boot

The pull-up on USB D+ is by default enabled, as needed by DFU mode. In
normal operation, we should disable it unless case-closed debugging is
enabled.

BRANCH=None
BUG=chrome-os-partner:33544
TEST=Build ryu

Change-Id: I18d216d8fff61640e4fbc3ce259209b3f149abf1
Signed-off-by: Vic Yang <5fd92abeee651458f98e2856f4f200ee971cee4d@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/229797
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
(cherry picked from commit 399a810103839ecf990c1add90156aa49d631317)
Reviewed-on: https://chromium-review.googlesource.com/230053
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>
Commit-Queue: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>
Tested-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

thehobn/ec,thehobn/ec,thehobn/ec,thehobn/ec