drm/amd/display: Refactor phantom resource allocation

[WHY?]
Phantom streams and planes were previously not referenced explcitly on creation.

[HOW?]
To reduce memory management complexity, add an additional phantom streams and planes
reference into dc_state, and move mall_stream_config to stream_status inside
the state to make it safe to modify in shallow copies. Also consildates any logic
that is affected by this change to dc_state.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Refactor dc_state interface

[WHY?]
Part of the dc_state interface that deals with adding streams and planes should
remain public, while others that deal with internal status' and subvp should be
private to DC.

[HOW?]
Move and rename the public functions to dc_state.h and private functions to
dc_state_priv.h. Also add some additional functions for extracting subvp meta
data from the state.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>