drm/amdgpu: disable default navi2x co-op kernel support

This patch reverts the following:
commit 48733b22 ("drm/amdkfd: add Navi2x to GWS init conditions")

Disable GWS usage in default settings for now due to FW bugs.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>