radeonsi: Allocate buffers for DCC.

radeonsi: Allocate buffers for DCC.

As the alignment requirements can be 32 KiB or more, also adding
an aligned buffer creation function.

DCC is disabled for textures that can be shared as sharing the
DCC buffers has not been implemented yet.

Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>