drm/amdgpu: The interrupt source was not released

When the driver is unloaded, the interrupt source of
the rma device is not released, resulting in the failure
of hw_init when loading again using bad_page_threshold.

Signed-off-by: Ce Sun <cesun102@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>