drm_hwcomposer: Tidy-up DrmDevice class

drm_hwcomposer: Tidy-up DrmDevice class

1. Move drm/DrmConnector.h to Normal clang-tidy checks list by fixing
   clang-tidy findings.

2. Remove DrmDevice self-reference.

3. Replace shared_ptr reference to DrmDevice in DrmFbImporter with a
   pointer, making ResourceManager only owner of DrmDevice and its
   chilren.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>