drm/amd/display: Copy DC context in the commit streams

DC adds an instance of DML (which contains VBA) to each context, and
multiple threads might write back to the global VBA resulting in data
overwriting. To keep the consistency with other parts of the DC code,
this commit changes dc_commit_streams to copy the current DC state, and
as a result, it also changes the function signature to expect streams
instead of a context.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>