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This CL adds logic for resetting all User Controls to its default
value upon closing the device file descriptor; otherwise, as the
bug proves, they persist across camera uses, e.g. the zoom level
is unchanged.

This would be relatively simple except for the fact that controls
come in two types: user controls and camera controls, and
that some controls need another one to be set or cleared
beforehand (e.g. white_balance_auto must be set to off
before white_balance can be set, etc).

See [1] for Spec
[1]  https://www.linuxtv.org/downloads/legacy/video4linux/API/V4L2_API/spec-single/v4l2.html#control

BUG=662616

Review-Url: https://codereview.chromium.org/2479413002
Cr-Commit-Position: refs/heads/master@{#437695}