drm/amdgpu: set ih chicken bit for IH 4.4.2

Share same register address with IH 4.4.0.

Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>