Eliminate unhelpful ERROR logging in accellerometer_reader.cc on linux

Eliminate unhelpful ERROR logging in accellerometer_reader.cc on linux

Running chrome built with chromeos=1 produces unhelpful ERROR messages
since the expected directories do not exist.

BUG=547836
Committed: https://crrev.com/47375bd08398676f5fb652077d69d543f6e8b556
Cr-Commit-Position: refs/heads/master@{#357390}

[stevenjb, 2015-10-26 17:32:39]

stevenjb@chromium.org changed reviewers:
+ jonross@chromium.org

[stevenjb, 2015-10-28 18:50:12]

stevenjb@chromium.org changed reviewers:
+ flackr@chromium.org

[stevenjb, 2015-10-28 18:50:12]

+flackr@

[jonross, 2015-10-30 13:43:11]

On 2015/10/28 18:50:12, stevenjb wrote:
> +flackr@

LGTM

[flackr, 2015-10-30 14:27:30]

lgtm

[stevenjb, 2015-11-02 18:07:51]

The CQ bit was checked by stevenjb@chromium.org

[commit-bot: I haz the power, 2015-11-02 18:08:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1428453002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1428453002/20001

[commit-bot: I haz the power, 2015-11-02 18:39:21]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-11-02 18:40:51]

Patchset 2 (id:??) landed as
https://crrev.com/47375bd08398676f5fb652077d69d543f6e8b556
Cr-Commit-Position: refs/heads/master@{#357390}