[sensors](CrOS/Linux) Rename SensorDeviceManager cc and h files.

It is a followup patch to https://codereview.chromium.org/2533793002/
In addition to renaming this CL fixes a typo in code where sensor
cache in erased.

BUG=606766

Review-Url: https://codereview.chromium.org/2560263002
Cr-Commit-Position: refs/heads/master@{#437778}
6 files changed