drm/amd/display: start using linux hdmi header

DAL has defines for things, and it doesn't even use them itself.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>