drm/amd/display: do not disable an invalid irq source in hdp finish

[why]
Observing error log about trying to disable non-implemented irq source
when user unload the driver.

[how]
Check and filter the invalid irq source before disabling it.

Reviewed-by: Qingqing (Lillian) Zhuo <Qingqing.Zhuo@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Alan Liu <HaoPing.Liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>