We cannot know how much current we can pull from video dongle, so let's
just try to pull as much as possible up to 2A.
BUG=chrome-os-partner:19324
TEST=Plug in video dongle and see 3.3V output.
TEST=Plug in video dongle with supplied charger, and see 50% PWM duty
cycle.
TEST=Plug in video dongle with normal charger, and see 70~80% PWM duty
cycle.
BRANCH=spring
Change-Id: I8b503f886fcafaa11e6757a5059ce673a8ed53cc
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/50963
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>