drm/amd/display: Add function for validate and update new stream

DC stream can be seen as a representation of the DCN backend or the data
struct that represents the center of the display pipeline. The front end
(i.e., planes) is connected to the DC stream, and in its turn, streams
are connected to the DC link. Due to this dynamic, DC must handle the
following scenarios:

1. A stream is removed;
2. A new stream is created;
3. An unchanged stream had some updates on its planes.

These combinations require that the new stream data struct become
updated and has a valid global state. For handling multiple corner cases
associated with stream operations, this commit introduces a function
dedicated to manipulating stream changes and invokes the state
validation function after that.

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>