drm_hwcomposer: CI: Find all source files instead of hardcoding them.

drm_hwcomposer: CI: Find all source files instead of hardcoding them.

Goals:

1. Follow clang-tidy rules to maintain project clean.

2. Do not allow new code to break goal #1.

Requirements for CI:

1. In case new file appears in the project, it should be picked-up by CI
   automatically and CI should assign NORMAL clang-tidy check level.

2. CI makefile should have SKIP list to define files for which build
   by CI is impossible for some reason.

3. CI makefile should have ability to override clang-tidy check level for
   every file.

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