drm/amd/display: Add case for dcn35 to support usb4 dmub hpd event

[Why & how]
Refactor dc_is_dmub_outbox_supported() a bit and add case for dcn35 to
register dmub outbox notification irq to handle usb4 relevant hpd event.

Reviewed-by: Roman Li <roman.li@amd.com>
Reviewed-by: Jun Lei <jun.lei@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>