drm/amd/display: Drop dc_commit_state in favor of dc_commit_streams

[Why & How]
There are two functions responsible for handling the DC commit state:
dc_commit_state and dc_commit_streams. Both have the same goal, but
dc_commit_streams surpess dc_commit_state in terms of completeness. For
this reason, maintaining these two functions makes maintainability
unnecessarily complicated. This commit replaces the old dc_commit_state
in favor of dc_commit_streams, and removes the old dc_commit_state.

Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>