drm/amd/display: refactor init_hw to isolate pipe related init

[Why]
Pipe related init is possible to optimized if we know what we
intend to program, and if we can determine it matches what is
already programmed for the pipe.

[How]
First step is to isolate the pipe related init code

Signed-off-by: Anthony Koo <[email protected]>
Reviewed-by: Aric Cyr <[email protected]>
Acked-by: Bhawanpreet Lakha <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
3 files changed