Add dual plane dcc programming support for
surfaces.

Removes unions from plane size and dcc params as they
serve no practical purpose only making our code
more convoluted. This results in easy dual plane
dcc and surface size programming.

Temporary diags_dm code is used to handle the interface
change without breaking functionality as a diags change
needs to be applied after this one.
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>