drm/amd/display: fix macro_tile_size for tiling

A regression was introduced when we set correct tile size
for the gfx9 swizzle mode. This resulted in incorrect
macro tile size.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>