Reorganize drm hal modules

Previously the drm and crypto plugins were separate hals.
This implied a separation of implementation libraries which
causes problems for some drm schemes. The reorganization
combines the hals into a single interface under drm.

Tests: basic gtests passing

Change-Id: I5cde6ff9f60625a0219731c4dbfcaefbd9f27f88
related-to-bug: 32815560