drm/amdgpu: fix handling of irq domains on soc15 and newer GPUs

We need to take into account the client id otherwise we'll end
up sending generic events for any src id that is registered.

We only support irq domains on pre-soc15 parts so client is
always legacy.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>