drm/amdgpu: Enable IH retry CAM on GFX9

This patch enables the IH retry CAM on GFX9 series cards. This
retry filter is used to prevent sending lots of retry interrupts
in a short span of time and overflowing the IH ring buffer. This
will also help reduce CPU interrupt workload.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>