Add logic for detecting hammerhead volume key input device

This allows mce to block volume key events from reaching the ui
unless allowed by policy.

The same input device node also sends events from magnetic lid sensor.
Blocking them from other processes does no harm as they should be
handled within mce anyway.

[mce] Add logic for detecting hammerhead volume key input device. Fixes JB#21638
Merge pull request #194 from spiiroin/hammerhead_volume_keys

Add logic for detecting hammerhead volume key input device